4th

ACTRIS General Meeting

June 10-13, 2014, Clermont-Ferrand, France

Meeting Program

Program Overview

Detailed Program with abstracts

Opening

Tuesday, 10 June, 14:00 – 14:30

14:00 – 14:15 Welcome addresses

Patrick Bachelery (OPGC) Joel van Baelen (CNRS - LaMP)

14:15 – 14:30 Introduction

Paolo Laj (CNRS-LGGE/UJF) / Gelsomina Pappalardo (CNR-IMAA)

Oral session S1a: Scientific achievements at ACTRIS stations

Tuesday, 10 June, 14:30 – 17:00

Chairs: Herman Russchenberg, Alfred Wiedensohler

S1.O1 (14:30 – 14:45) Using Cloudnet data to evaluate the representation of clouds in NWP models

A. J. Illingworth and E. J. O'Connor

Cloud data from the recently extended ACTRIS advanced atmospheric observatories

have been compared with the representation of clouds in various nwp models. Skill

scores have been derived which quantify the ability of the weather forecast models

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to predict the right clouds in the right place at the right time; this is a necessary first

step if the models are to predict heavy rainfall events. Both climate and weather

forecasting models use essentially the same cloud parameterisation schemes so the

performance of various schemes in forecast models is a useful guide of their

suitability for use in climate models.

S1.O2 (14:45 – 15:00) Analysis of microphysical properties at EARLINET stations: spatial and temporal evolution during summer 2012 operational exercise M. J. Granados-Muñoz, F. Navas-Guzmán, J. L. Guerrero-Rascado, J.A. Bravo-

Aranda, S. N. Pereira, M. Sicard, L. Belegante, D. Nicolae, A. Papayannis, G.

D’Amico, K. Schepanski, J.M. Baldasano, U. Wandinger, A. Chaikovsky, G.

Pappalardo, C. Muñoz, A. Rodríguez, A. Comerón and L. Alados-Arboledas

In the framework of an exercise to test the operational capabilities of

ACTRIS/EARLINET during Summer 2012, intensive measurements were performed in

July 2012 during a period of 72-hour simultaneously at several ACTRIS/EARLINET

ground-based lidar stations. One of the aims of this exercise regarding lidar

measurements was to obtain an experimental database with vertical resolution for

investigating the aerosol radiative impact over the Mediterranean basin using 3-D

model simulations of African dust. The exercise was held from 9th July at 06:00 UTC

to 12th July at 06:00 UTC, when a mineral dust event was affecting the European

region. Besides the lidar measurements, five of the stations performed coincident

sun photometers measurements following AERONET protocols, i.e. Granada,

Athens, Évora, Barcelona and Bucharest. The combined AERONET/EARLINET

measurements allow here for analysing vertical profiles of microphysical properties

by means of LIRIC (Lidar Radiometer Inversion Code) algorithm. By combining lidar

measurements and AERONET inversion retrievals at the five experimental sites,

volume concentration profiles of fine and coarse particles (spherical and spheroid

when available) are retrieved. The obtained results allow us to analyze both

temporal and spatial evolution of the vertically resolved microphysical properties of

mineral dust during the 3-day intensive measurement period, improving our

knowledge about the different processes affecting mineral dust during its transport.

Data from models such as BSC-DREAM8b, SKIRON, NAAPS and COSMO-MUSCAT

will also be validated by means of these retrievals.

S1.O3 (15:00-15:15) Aerosol Mass Spectrometric Measurements at CESAR-Tower in Cabauw, NL,

P. Schlag, A. Kiendler-Scharr, A. Vermeulen, M. J. Blom, R. Holzinger

Intensive measurements of aerosol chemical composition were performed with an

Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS)

at the Cabauw Experimental Site for Atmospheric Research (CESAR) in Cabauw, NL,

in November 2011 and from May to July 2012. Additionally, an Aerosol Chemical

Speciation Monitor (ACSM) was measuring from July 2012 to June 2013. The CESAR

site is a rural station representative for North-West Europe. Depending on

prevailing wind direction, the condition can be either of maritime or continental

character.

As observed in previous campaigns at the site, nitrate and organics are major

contributors to aerosol mass with their relative importance showing a seasonal

dependence. Inorganic and organic aerosol composition data from the AMS are

compared with Monitor for AeRosol and GAses (MARGA) and a Thermo-Desorption-

Proton-Transfer-Mass-Spectrometer (TD-PTR-ToF-MS), respectively. Evaluating the

inorganic ion balance, we observe periods in which observed NH4+ exceeds the

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NH4+ needed for inorganic anion neutralization. This is taken as indication for the

presence of organic acids in the aerosol. For the first time, Positive Matrix

Factorization (PMF) was used for analysing the aerosol organic fraction derived

from the TD-PTR-MS. These and the PMF results from the HR-ToF-AMS show

similarities in time trends of AMS and PTR-MS factors. That creates new possibilities

to analyse PMF factors with mass spectra from two different ionization techniques.

Main organic aerosol sources and the possibility to quantify organic acids based on

AMS data in environments with high NH3 are discussed.

S1.O4 (15:15 – 15:30) Typifying Air Masses and Sources at Birkenes in Southern Norway by Combining

ACTRIS Observables and Model Tools

M. Fiebig, W. Aaa, S. Solberg, N. Schmidbauer, A.M. Fjæraa, K.E. Yttri, T.

Hamburger, C.R. Lunder, C. Lund Myhre, K. Tørseth, G. Hansen

We propose that a cluster analysis on data from ACTRIS stations can serve as basis

for a pan-European parameterization of aerosol properties as new integrated

ACTRIS product for use in climate modelling. The method is exemplified using

Birkenes atmospheric observatory in Southern Norway, which is uniquely located to

study biogenic boreal forest emissions, long-range transported pollution from

industrialised regions, Arctic in- and outflow, as well as regional emissions in a

sparsely populated Northern landscape, all at the same location. Over the past

years, the Birkenes observation programme, contributing to ACTRIS WP3 and 4, has

been upgraded to now include almost the full list of aerosol parameters

recommended by GAW for long-term observation (particle size distribution,

scattering / absorption coefficient, concentrations of particle mass, major chemical

constituents, and cloud condensation nuclei, columnar optical depth), as well as

gas-phase components such as offline VOCs, CO_2 , CH_4 , O_3 , PCBs, also

precipitation chemical composition. Recently, the programme has been augmented

further to include online aerosol chemical

speciation by ACSM (continuous), and online VOCs by PTR-MS (campaign-based).

Based on the observations of aerosol properties with high (hourly) time resolution,

a cluster analysis is presented that classifies the aerosol types

encountered at Birkenes into 4 classes, while the Lagrangian transport model

FLEXPART locates the footprint, i.e. source regions, of the 4 clusters. The analysis is

augmented by correlation with levoglucosan samples as tracer of

emissions from biomass burning. A further analysis uses 2 intensive campaigns of

PTR-MS VOC observations and the EMEP-WRF modelling system to investigate the

fate of biogenic VOC emissions.

15:30 – 16:00 Coffee break

S1.O5 (16:00 – 16:15) Diurnal and seasonal variability of the atmospheric boundary layer depths over

the suburban SIRTA observatory near Paris: Dynamics and forcing mechanisms

M. Haeffelin and S. Pal

The development and maintenance of the atmospheric boundary layer (ABL) plays a

key role in governing the distribution of atmospheric constituents like aerosols,

greenhouse gases, water vapor, ozone, etc. For instance, the ABL features (e.g.,

depth, turbulent flux, entrainment processes, and growth rate) are important for

understanding air quality impacts of aerosols, and the dispersion and transport of

aerosols confined within the ABL. A detailed understanding of these features based

on long-term measurements of ABL depths is considered challenging but important

for meteorological process studies involving ABL depths.

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A long-term data set of ABL depth time series has been derived at the SIRTA

observatory near Paris, using measurements obtained from a ground-based

vertically-pointing aerosol lidar system and a robust retrieval method. Five years of

observations (2008-2013), are used to investigate both diurnal and seasonal

variability of ABL depths and their correlation to near-surface meteorological

parameters (e.g. near-surface stability condition, humidity, temperature, sensible

heat flux, etc.). We found that the day-to-day variability in the ABL depths to be

affected not only by site-specific meteorological conditions (e.g. solar radiation,

precipitation, low-level cold-air advection, near-surface meteorological

characteristics), but also by land-surface characteristics, cloud cover, dynamical

features associated with the interplay between residual layer and the nocturnal

boundary layer (NBL), and synoptic conditions. Additionally, the ABL depths show

larger day-to-day variability on fair weather days than on cloudy and synoptically-

disturbed days on which ABL depths are poorly defined. For instance, the process of

destruction of the inversion layer is defined as the breakup of the temperature

inversion which is destroyed predominantly by the upward growth of a convective

boundary layer from the ground. By analyzing diurnal-cycle composites of ABL

depths, we document characteristic features of the driving factors that determine

both diurnal and seasonal variability in the daytime CBL depths over SIRTA.

S1.O6 (16:15 – 16:30) Phenomenology of aerosol absorption at Montseny (regional background) and

Montsec (mountaintop) stations in NE Spain

M. Pandolfi, N. Pérez, A. Ripoll, X. Querol, M. C. Minguillón, and A. Alastuey

(IDAEA-CSIC, Barcelona, Spain)

Aethalometer (AE31 and AE33) and MAAP instruments were deployed to

investigate time trends, seasonal dependence and diurnal cycles of aerosol

absorption at Montseny (MSY; regional background; 720 m a.s.l.) and Montsec

(MSC; remote; 1570 m a.s.l.) stations in NE Spain. The multiwavelenght

Aethalometer data were used to apportion aerosol absorption, black carbon (BC),

elemental carbon (EC) and organic carbon (OC) concentrations to fossil (ff) and

non‐fossil (biomass burning; bb) sources. Results showed that the Aethalometer

source apportionment appeared to be more robust for apportioning the

contributions of each source to BC and EC rather than to OC probably as a

consequence of the high biogenic contribution to OC concentrations at MSY and

MSC stations. Aerosol absorption data from MAAP and EC concentrations from

filters were used for the determination of the mass absorption cross section (MAC)

at both measurement sites. The results show that the MAC was clearly a function of

seasons and air mass origin at both sites indicating changes in the microphysical

properties of absorbing particles depending on aerosol type and aging. In order to

investigate the reasons for the observed variation of the MAC chemical speciated

PM data from filters (24h resolution) and from an ACSM instrument (30 min

resolution) were used. Finally, the data collected at MSC station, frequently in the

free troposphere, were used to investigate the importance of mineral matter

(mainly Iron) absorption on MAAP data.

S1.O7 (16:30 – 16:45)

ACTRIS intercomparison experiment of volatile organic compounds in Europe

C. C. Hoerger, A. Werner, C. Plass-Duelmer, S. Reimann, E. Eckart, R. Steinbrecher,

J. Arduini, N. Bonnaire, J. N. Cape, A. Colomb, R. Connolly, J. Diskova, P. Dumitrean,

C. Ehlers, V. Gros, H. Hakola, M. Hill, J. R. Hopkins, J. Jäger, R. Junek, M. Leuchner,

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A. C. Lewis, M. Maione, D. Martin, K. Michl, E. Nemitz, S. O'Doherty, S. Sauvage, N.

Schmidbauer, T. G. Spain, E. Straube, M. Vana, M. K. Vollmer, R. Wegener, A.

Wenger

During 2012, the performance of 20 European laboratories involved in long-term

VOCs measurements within the framework of GAW and EMEP was assessed with

respect to newly determined ACTRIS data quality objectives (DQOs). Compared to

previous intercomparisons the DQOs of ACTRIS are much more demanding

(deviations of max 5% to a reference value). The participants were asked to

measure a 30 component VOCs mixture (including alkanes, alkenes, alkynes, and

aromatic compounds) in nitrogen at about 1 nmol/mol and whole air following a

standardised operation procedure. For VOCs in nitrogen 61% of the FID- and 51% of

the MS-results were within the ACTRIS DQOs. For whole air slightly more scatter

was observed. The results of the analytical systems are discussed with respect to

calibration issues, FID and MS detection, sample matrices, breakthrough,

adsorptive losses, and chromatographic resolution. The results of monoterpenes

and trimetylbenzenes are shown in an accompanying poster by Werner et al.

S1.O8 (16:45 – 17:00)

ParisFog: a research program to better understand the fog processes combining

in-situ and remote-sensing instrument at SIRTA ACTRIS observatory

J-C. Dupont, M. Haeffelin, T. Elias, J. Delanoe, F. Burnet, J. Sciare, E. Dupont, P.

Goloub, T. Bourcy, F.Zanghi

Fog life cycle is driven by the competing interactions between thermodynamics,

dynamics, microphysics, radiative fluxes and chemistry all of which are difficult to

model. Therefore, the goal of this work is to combine in-situ sensors, active, and

passive remote sensing instruments to better understand dynamical, radiative,

thermal and turbulent processes modulating the different phases of the fog life

cycle.

The understanding of the physical processes needs to have precise retrievals along

the vertical for droplet and aerosol microphysical properties. So, in this presentation

we will focus on lidar and cloud radar algorithms for comparison with in-situ sensor

at the surface and retrieval along the vertical.

In a second part, we will present and quantify the critical values that key variables

must take to lead to fog formation and fog dissipation for all the different Low

Visibility Events (LVE) considered in this study. The statistical analysis used the

unique and coherent dataset derived from the in-situ, passive and active remote

sensing instruments deployed during the ParisFog field experiment since 2006 at

SIRTA observatory [Haeffelin et al., 2005, 2010].

Poster session P1: ACTRIS Integration activities

Tuesday, 10 June, 17:00 – 19:00

P1.1 EARLINET/ACTRIS support to the summer 2013 ADRIMED/ChArMEx campaign

Michaël Sicard, Constantino Muñoz, Adolfo Comerón, Lucas Alados‐Arboledas, Aldo Amodeo, Antonella Boselli, Giuseppe D'amico, María José Granados‐Muñoz, Giuseppe Leto, Juan Luís Guerrero‐Rascado, Fabio Madonna, Lucia Mona, Gelsomina Pappalardo, Maria Rita Perrone, Simona Scollo, Nicola Spinelli, Gloria Titos, Xuan Wang, Ricardo Zanmar Sanchez

In the framework of the ChArMEx (Chemistry‐Aerosol Mediterranean Experiment,

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http://charmex.lsce.ipsl.fr/) initiative, a field campaign took place in the western

Mediterranean Basin between 10 June and 5 July 2013 within the ADRIMED

(Aerosol Direct Radiative Impact on the regional climate in the MEDiterranean

region) project. The scientific objectives of ADRIMED are the characterization of

the typical “Mediterranean aerosol” and its direct radiative forcing (column

closure and regional scale). At three sites, in Ersa (Corsica Island, France),

Granada (Spain) and Lampedusa (Italy), a complete set of instruments were

operated to measure in‐situ aerosol physical, chemical and optical properties.

Aerosol mixing state and vertical distribution, as well as radiative fluxes were also

measured. At a third site, in Menorca (Spain), aerosol optical properties and

vertical distribution were measured. The ground observations were supported by

airborne measurements: the ATR‐42 (10 June – 5 July) and the Falcon‐20 (17 June

– 5 July) equipped with a lidar. In several occasions corresponding to aerosol loads

of different types the aircrafts flew near EARLINET/ACTRIS lidar stations: near

Barcelona and Granada on 16 and 17 June, near Barcelona on 18 and 27 June,

near stations in southern Italy (Potenza, Naples, Lecce, Serra La Nave) on 22, 23,

28 June and 2 July. Whenever it was possible, extra measurements were carried

out by the EARLINET/ACTRIS lidar stations. The presentation will focus on the

situations covered simultaneously by airborne and ground‐based lidar

measurements.

P1.2 On the usefulness of ceilometers for aerosol monitoring

Matthias Wiegner and Alexander Geiß

With the implementation of ceilometer networks by national weather services a

discussion started to which extent these simple backscatter lidars can be used for

aerosol research. Though primarily developed for the detection of clouds several

publications show that at least observations of the vertical structure of the

boundary layer might be possible. Quantitative retrievals of optical properties of

particles are, however, restricted to the backscatter coefficient βp. These

retrievals require the calibration of the ceilometer.

Calibration is possible, if issues as incomplete overlap, sampling properties when

compared to sun photometer measurements, the unknown lidar ratio, and water

vapor absorption are carefully considered. EARLINAT lidars can be of great help

for calibration purposes. For the derivation of βp forward and backward

integration methods are available – with different performance with respect to

accuracy and applicability. An extended discussion of the different options can be

found in Wiegner et al. (2014). Under favorable conditions the uncertainty of βp

will remain below 10%, a high temporal resolution of a few minutes can be

achieved, and near real time applications are possible.

Calibrated signals are also beneficial for basic applications such as the assessment

of the mixing layer height or the detection of elevated aerosol layers. The

combination of methods for edge detection and edge tracking techniques results

in a high reliability. Consequently, and as the maintenance costs of ceilometers

are low and operation is fully automated, long term observations of the

stratification of the tropospheric aerosols are feasible.

P1.3 Major updates and improvements of the EBAS database and web portal

T. Hamburger, M. Fiebig, P. Eckhardt, W. Aas, A.M. Fjæraa, C. Lund Myhre, K.

Tørseth

The EBAS database hosts observational data of atmospheric chemical and

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physical properties. The increase in content and usage by a multiplicity of different

groups led to a growing demand on the database functionality. Several

improvements and changes concerning the database core and user interface were

determined and implemented to support the present and future requirements on

the EBAS database.

Within the new implementation a suite of new tools have been developed to

support the QA/QC process and for extracting statistical information.

The data export format is adapted to user suggestions to improve the

interoperability with further applications. Mass download and scheduled data

transfer is implemented for several projects. Amongst others, a regular data

export for Met.no (aerosol NRT data) and HTAP (quarterly extract) as well as a

daily extract for the ECMWF and MACC project is set up.

New implementations in the EBAS web interface improves the performance and

usability of the web application during start up and data selection. Several bugs

are corrected in the web representation of EBAS and its online visualisation tools.

Within the development of the ACTRIS Data Centre new online visualisation

methods are implement and will be ported to the EBAS web interface in the

future.

One of the main new features is the improved usage of metadata elements.

New metadata elements are added to support the version control of datasets.

This allows for a full history of the database and data sets, to track data updates

and retrieve historic data versions. Metadata elements can be time-dependent

and changes can be tracked. Hence, integration into e.g. INSPIRE and GCOS are

therefore enabled. The new metadata features improve the traceability of the

data processing back to their observations. In addition, new metadata elements

were implemented to support descriptions for advanced aerosol observations as

part of GAW-WDCA.

We will present the features and updates of the new EBAS database and web

application at the ACTRIS GA.

P1.4 Testing for loading effects in filter photometers – how to avoid assumptions

altogether

G. Močnik, L. Drinovec, T. Hansen, S. Segura, V. Estellés, G. Titos, H. Lyamani, M.P.

Utrillas, P. Zotter, A.S.H. Prévôt, L. Alados-Arboledas, J.A. Martínez-Lozano, A.

Polidori, M. Rupakheti, G. Schauer

Filter absorption photometer measurements are affected by loading effects which

need to be compensated. Various compensation methods relied mostly on the

continuity of data (Weingartner et al. 2003; Virkkula et al., 2007; Hyvärinen et al.,

2013) to derive the compensation parameters. Here we propose a more robust

method to determine the quality of the compensation for loading effects: the

slope of the absorption coefficient vs. the loading of the spot. This method was

used to compensate the BC measurements (Park et al., 2010), but here we use it

as an independent criterion to evaluate the compensation. This criterion does not

use any assumptions or external data, only the measurements from a single

instrument by checking the measured parameters for internal consistency. For a

long period of homogeneous measurements in terms of the sources and

meteorology, the absorption coefficient should not depend on the loading of the

spot. The uncompensated measurements of mass equivalent Black Carbon in filter

photometers are proportional to the time derivative of the attenuation of

detected light intensity (MAAP: in reflection; Aethalometer: in transmission), not

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on the absolute attenuation values. Any dependence of the measured absorption

on the loading (attenuation) is evidence of a bias due to the loading of the spot.

The parameter, which was shown to be most representative of these effects, is the

slope of the attenuation or absorption coefficient or attenuation coefficient as a

function of the loading. We will demonstrate the usefulness of this method as an

independent criterion of the compensation for several absorption photometers

from different campaigns: the MAAP, Aethalometer AE31, AE33.

P1.5 ACTRIS mass closure experiments for gaseous and particulate carbons at

different stations in Europe

C. C. Hoerger, S. Reimann, M. Hill, A. Werner, C. Plass-Duelmer, J. K. Gietl, K.

Michl, M. Crippa, A. Prévôt, N. Bonnaire, A. Borbon, V. Gros, N. Marchand, V.

Riffault, S. Sauvage, J. Sciare, A. Setyan, B. Bandy, J. R. Hopkins, D. C. Green, D.

Young

A new approach for holistic consideration of the total observed organic carbon

(TOOC) budget will be shown at different sites in Europe. Similar budget

approaches are routinely used for nitrogen oxides and sulfur in the atmosphere,

and rapidly improving measurement techniques (such as ACSM or PTR-MS) are

beginning to make this possible for organic carbon. The organic carbon budget

includes a large group of compounds, with many that are likely to contribute have

hardly been observed under ambient conditions. Therefore, the combined analysis

of gaseous compounds, which play an important role in the chemistry of the

troposphere, and particles, which are a climate forcing agent, is an important

issue. This mass closure of atmospheric organic carbon will be achieved by

bringing together state-of-the-art equipment for both gaseous and particulate

organic substances (GC-FID/GC-MS/PTR-MS/ACSM). Preliminary TOOC-results of

some sites, which were involved in EMEP intensive campaigns, MEGAPOLI, or

ClerFlo, will be presented.

P1.6 Intercomparison of ME-2 source apportionment results from 15 co-located

aerosol mass spectrometers from the ACTRIS-ACSM network

Roman Fröhlich, Vincent Crenn, Francesco Canonaco, Jay G. Slowik, Olivier Favez,

Wenche Aas, Mikko Äijälä, Begoña Artiñano, Claudio A. Belis, Michael Bressi,

Claudio Carbone, Esther Coz, Philip L. Croteau, Michael J. Cubison, Johanna K.

Gietl, David C. Green, Liine Heikkinen, John T. Jayne, María C. Minguillón, Colin D.

O’Dowd, Jurgita Ovadnevaite, Ettore Petralia, Laurent Poulain, Max Priestman,

Véronique Riffault, Anna Ripoll, Roland Sarda-Estève, Ari Setyan, Urs

Baltensperger, Jean Sciare and André S. H. Prévôt

14 mass spectrometers for on-line aerosol particle chemical composition

measurements (13 Quadrupole ACSM, 1 ToF-ACSM) from the ACTRIS-ACSM

network (http://www.psi.ch/acsm-stations) and one HR-ToF-AMS were gathered

at the SIRTA site in Gif-sur-Yvette, approximately 20km southwest of Paris. From

15.11.2013 to 02.12.2013 all 15 instruments measured ambient aerosol in parallel

and with the same settings with the aim to improve the understanding of the

measurement technique and its related uncertainties

This presentation focuses on the intercomparison of widely and successfully used

positive matrix factorization (PMF) source apportionment strategies for aerosol

mass spectrometer data (Paatero & Tapper, 1994; Lanz et al., 2007) using the

new source finder (SoFi, Canonaco et al., 2013) toolkit based on the Multi-linear

Engine 2 (ME2) solver.

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Fig. 1 summarizes the 4-factor source apportion-ment results, generated

individually for each dataset of the 15 instruments using optimized a-values for

HOA and COA, with anchor mass spectra taken from a previous campaign at the

same site (Crippa et al. 2013). The average contributions of the factors to the total

organics are: HOA: 14.8±2.3%; COA: 16.0±2.6%; OOA: 39.4±4.9%; BBOA:

31.0±3.5%. These results present an accuracy of the source apportionment factors

across the 15 different instruments of about ±20%.

Several other parameters like the variability of the individual factor mass spectra

or the influence of the employed reference spectra were explored as well.

P1.7 Atmospheric Observatory Eastern Mediterranean

L. Barrie, Nikos Mihalopoulos, H.C. Hansson, Vangelis Gerasopoulos, Jean Sciare,

M. Vrekoussis, S. Kleanthous, Zev Levin

The Eastern Mediterranean is a unique yet poorly observed region for atmospheric

chemistry. Surrounded by the diverse ecosystems and populations of southern

and Eastern Europe, the Middle East and North Africa, it experiences a diverse

mix of anthropogenic, biogenic and natural aerosols. Sand and dust storms from

northern Africa, the Gulf region and Middle East are frequent and severe. Aerosols

from biomass burning fires in the arid summer half of the year is common.

Anthropogenic sulphates, nitrates and organics are produced from gas to particle

conversion and advected into the region from many sources. These aerosol types

often mix with sea salt aerosols in the moist planetary boundary layer of the

Mediterranean.

Although there are comprehensive air chemistry observations at individual

stations over the region that are registered with ACTRIS, they are largely

uncoordinated. In Crete, the Finokalia station has been operating for twenty

years. In Cyprus, the Agia Marina station has been operating as a regional station

in the Cooperative Programme for Monitoring and Evaluation of the Long-range

Transmission of Air Pollutants in Europe (EMEP) for over 15 years and is imbedded

in a 9 station environmental network. In addition in Cyprus, there is an aerosol

remote sensing LIDAR and AERONET photometer operated under ACTRIS as well

as Unmanned Aircraft operated under the European project BACCHUS.

In the Peloponnese region of western Greece, the Navarino Environmental

Observatory has been measuring aerosols for several years. It is proposed that a

consortium focusing on the Atmospheric Observatory Eastern Mediterranean is

developed as part of the future European aerosol and atmospheric chemistry

observing infrastructure. One key goal is to utilize existing expertise in the

consortium to build capacity for atmospheric observations and research in the

region.

P1.8 Atmospheric Station and UAV Facilities in Cyprus: A New Tool for Coupling In-

Situ, Remote Sensing And Vertical Atmospheric Observations

L. Barrie, M. Vrekoussis, S. Kleanthous, J. Sciare, N. Mihalopoulos, Z. Levin, M.

Lange, M. Argyrides, S. Ioannou, C. Keleshis, R. Sarda-Estève, F. Dulac, G. Roberts,

M. Mallet, G. Mocnik

The island of Cyprus is strategically located at a crossroads of air streams from

Europe, Africa and the Middle East that have contrasting aerosol-related

emissions from natural and anthropogenic sources. It is in a Mediterranean region

where climate changes (e.g. heat waves and droughts) are expected to be among

the highest globally (IPCC, 2011). Also, Cyprus experiences a large number of dust

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storms originating from Africa, the Gulf region and the Middle East which

exhibiting different and poorly characterized aerosol optical properties (Mamouri

et al., 2013).

Since the late nineties, long term observations of key atmospheric chemistry

variables (O3, NOx, PM) have been initiated in Cyprus, at the “Agia Marina

Xyliatou” station (Figure 1) operated by the Department of Labor Inspection as a

European Monitoring and Evaluation Programme (EMEP) station focusing on

long-range transboundary air pollution (Kleanthous et al., 2014). As part of the

ENVIMED “CyAr” project (component of the French ChArMEx program;

http://charmex.lsce.ipsl.fr/), this station will be equipped by mid 2014 with a new

set of real-time in-situ aerosol instruments (Q-ACSM, 7-l aethalometer, 3-l

nephelometer, OPC, SMPS, CCN counter) offering new perspectives on aerosol

(PM) sources and their geographical origin downwind of major non–EU countries

surrounding the Mediterranean (Turkey, Lebanon, Israel, Egypt) as well as on

properties of sand and dust storms.

In parallel, the Cyprus Institute (CyI) has developed a fleet of Autonomous

Unmanned Aerial Vehicles (UAV, Figure 2) equipped with ultra-light aerosol

sensors (absorption, number size distribution electrostatic precipitator for ice

nuclei) to measure vertical profiles. As part of the EU-FP7 BACCHUS project

(http://www.bacchus.ethz.ch/) and in conjunction with LIDAR observations

performed by the Cyprus University of Technology, the UAVs will be deployed from

spring 2015 to investigate ice nuclei (IN) and cloud condensation nuclei (CCN) and

other aerosol properties.

The coupling between the ground based measurements at Agia Marina Xyliatou

Station and UAV vertical profiles will constitute a unique new data sets to

characterize the respresentativeness of the surface in situ measurements.

As a proof of concept, new light multi-wavelength absorption sensors are being

tested on the CyI UAVs in 2015 and compared with similar sensors at ground level

to explore the spectral absorption dependence of African and Middle Eastern dust

particles. These vertical absorption measurements will help to constrain and

calibrate aerosol remote sensing instrumentation operated by the ACTRIS

community.

P1.9 Preliminary results of testing of regularization algorithm for data processing of

Raman and polarization lidar measurements

Anatoli Chaikovsky, Oleg Dubovik, Sergei Denisov, Yan Grudo, Anton Lopatin,

Yana Karol

Recent talk presents preliminary results of testing of new version of LIRIC (Lidar

and Radiometer Inversion Code) software package. Retrieving of aerosol

parameters from lidar data has properties of ill-posed inverse problems, as soon

as we turn from single-wavelength solutions of the lidar equation to processing

data of complex measurements. LIRIC inversion algorithm and program package

for retrieving concentration of aerosol modes from combined lidar and radiometer

data has been improved to process data of Raman and polarization lidar

measurements using common statistical regularization technique. Specific

program module for estimation of the uncertainty of the solutions has been

developed and included into the LIRIC package. Output database was modified to

include additional retrieved parameters.

P1.10 Canister experiment during the ACTRIS NA 4 VOC Round Robin intercomparison

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S. Sauvage, N. Locoge, S. Dusanter, C. C. Hoerger, A. Werner, C. Plass-Duelmer, S.

Reimann, E. Eckart, R. Steinbrecher

Non-Methane Hydrocarbon compounds (NMHCs) are tracers of both biogenic and

anthropogenic emission sources and play a key role in the atmosphere as

precursors of ozone or secondary organic aerosols. The importance of these

species for understanding atmospheric chemistry is recognized by the research

community and high-quality and long-term observations are needed to tackle

issues of air quality and climate change. Among methods to measure NMHCs,

whole air sampling in stainless steel canisters remains widely used within the

EMEP and GAW networks.

We included this method in the ACTRIS VOC Round Robin intercomparison

organized in 2012 to assess the reliability of this off-line method together with on-

line instrument testing at concentration levels of NMHCs around 1ppb. Samples in

canisters were analyzed by GC/FID to quantify 30 compounds from C2 to C9. The

results show a good agreement with online measurements for most compounds,

confirming the reliability of this method for monitoring volatile organic

compounds at low levels. It was also the opportunity to test the effect of several

parameters, namely the humidity of the sample, the canister pressure, and the

stability of the sample over time. These results are useful to better estimate the

measurement uncertainty.

P1.11 Intercomparison of ambient BVOC measurements: What useful information can

we infer for the ACTRIS program?

V. Michoud, S. Dusanter, S. Sauvage, N. Locoge, V. Gros, T. Léonardis, B. Bonsang,

C. Kalogridis

Biogenic Volatile Organic Compound (BVOCs) are of prime interest for long term

monitoring since these species contribute to the loading of organic carbon at

remote sites and are useful to evaluate models of atmospheric emissions. It is

therefore important to assess whether reliable measurements of BVOCs can be

performed using current techniques, which in turn will help assessing data quality

in measurement networks such as ACTRIS.

An intercomparison involving three online gas chromatographs, an automatic

cartridge sampler, and a Proton Transfer Reaction-Time of Flight Mass

Spectrometer from Mines Douai and the Laboratoire des Sciences du Climat et de

l’Environnement took place during Summer 2013 at Cap Corsica (France) as part

of the ChArMeX field campaign. These instruments measured continuously

ambient concentrations of isoprene and several monoterpenes (α- and β-pinene,

limonene, α- and γ-terpinene, camphene) for a duration of three weeks.

Collocated measurements have been compared to assess the reliability of BVOC

monitoring and to identify potential measurement artifacts. These results suggest

a good agreement between several techniques for isoprene but some differences

are observed for α- and β-pinene, as well as limonene. Some recommendations

will be provided for monitoring these species.

P1.12 ACTRIS carbonaceous data quality assessed over the years 2007-2013.

Fabrizia Cavalli and Jean-Philippe Putaud

Inter-laboratory comparison exercises for total and elemental carbon

measurement have been regularly organised in the framework of the EU-projects

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EUSAAR and ACTRIS over the period 2007-2013. The main objective has been to

assess the quality of data produced by individual site and in particular, to identify

and correct possible procedural and instrumental biases, derive site-specific

harmonisation factors and produce a highly comparable dataset at all sites.

Initially, the overall data comparability has substantially increased because of the

adoption of the common thermal-optical protocol EUSAAR_2 and the

implementation procedural recommendations.

Most recent exercises have revealed only slightly, if at all, improvements. The non-

negligible variability still existing in total carbon determination appears to be

user-dependent, whereas that one, even more pronounced, in the elemental

carbon determination is mainly due to an inter-instrument variability.

P1.13 Pathfinder: MLH temporal development tracking applying Dijkstra’s graph

search algorithm

Marco de Bruine , Arnoud Apituley, Fred Bosveld, Henk Klein Baltink

The height of the atmospheric boundary layer, or mixing layer (MLH) is an

important parameter for understanding the dynamics of the atmosphere and

dispersion of air pollution. Mixing layer heights can be retrieved from backscatter

lidar or ceilometer data. Various algorithms have been proposed, that all have in

common that the atmospheres aerosol content is used as a tracer for the layering

structure in the atmosphere. Although it is possible to detect gradients in the

vertical backscatter profile under most circumstances, the challenge lies in the

correct attribution of the detected gradients to the actual MLH. Tracking the MLH

can be challenging in complex cases, such as under the presence of residual layers

of air pollution above the MLH or during and after periods of rain. We pre--‐ sent a

new approach using Dijkstra’s graph search algorithm [Dijkstra, 1959] to be able

to find the optimal temporal development of the MLH. We show results from our

new ‘Pathfinder’ algorithm applied to Leosphere ALS450 data and veri--‐ fy the

results using wind profiler turbulence data and sounding profile retrievals

(Richardson bulk). Furthermore, we compare against MLH results from STRAT2D

[Morille, 2007] applied to the same data. We find that the Pathfinder approach

outperforms STRAT2D in particular during the periods of the development of the

MLH in the morning and in the evening. Also, during periods of broken clouds, we

find Pathfinder is able to better follow the development of the MLH. We hope to

be able to show some cases comparing to MLH retrievals from Doppler lidar data

[Harvey, 2013] as this will provide a better independent verification of turbulent

atmospheric structures. References E. W. Dijkstra, A note on two problems in

connexion with graphs, Numerische Mathematik, Vol. 1:1, pp 269--‐271, 1959

Morille, Y., M. Haeffelin, P. Drobinski, J. Pelon, 2007: STRAT: An automated algo--‐

rithm to retrieve the vertical structure of the atmosphere from single--‐channel

lidar data. Journal of Atmospheric and Oceanic Technology, 24, 761--‐775. Harvey,

N.J., Hogan, R.J., Dacre, H.F., A method to diagnose boundary--‐layer type using

Doppler lidar, Q. J. R. Meteorol. Soc. 139: 1681 – 1693, 2013.

P1.14 Earlinet intensive observation period during summer 2012

N. Papagiannopoulos, G. D’amico, A. Giunta, G. Pappalardo, L. Alados Arboledas,

A. Amodeo, L. Belegante, M. Iarlori, D. Lange, R.E Mamouri, M.A.P. Mcauliffe, D.

Nicolae, P. Kokkalis, J. Preissler, J. Putaud, J.L. Guerrero Rascado, V. Rizi, A.A Ruth,

M. Sicard, F. Wagner, L. Mona

13

An ACTRIS measurement campaign was organized during summer 2012, 8 June –

17 July. ACTRIS and EMEP closely worked together to coordinate this field

campaign which was mainly aimed at the study of Saharan dust particles. Besides,

this intensive observation period (IOP) featured two international field campaigns

during summer 2012 to optimize any possible cooperation. The ChArMEx (The

Chemistry-Aerosol Mediterranean Experiment, https://charmex.lsce.ipsl.fr/)

campaign was held in the period of from 8 June – 12 July and the PEGASOS (Pan-

European Gas-AeroSOLs-climate interaction Study, http://pegasos.iceht.forth.gr/)

campaign provided detailed measurements for the period from 8 June - 9 July.

The main objective of the EARLINET/ACTRIS campaign during summer 2012 was

to investigate the 3-D distribution of European atmospheric aerosols in the

context of Saharan dust intrusion events. The whole network participated in the

campaign performing EARLINET regular measurements. Additional measurements

were performed after alerts concerning the occurrence of special events over

Europe. 10 selected ACTRIS lidar stations performed daily lidar-profiling

measurements around sunset for the whole 8 June – 17 July 2012 period. The

availability of EARLINET vertical profiles of the aerosol optical properties during

the selected period strongly enhanced the collection of a unique, high quality data

set on aerosol, as gathered by a set of sophisticated instruments across Europe.

The description of aerosol type distribution over Europe during the campaign was

obtained through a combined use of advanced lidar measurements, backward

trajectory analyses and model outputs. In particular, two intense African dust

outbreaks were noted and studied into details.

P1.15 In-situ sampling and column remote sensing

Stefan Kinne

Many ACTRIS efforts monitor (sparsely distributed) atmospheric detail near the

surface. This has a lot of relevance to pollution and air-quality. But in order to

extend the value of these samples in space and time, ties to satellite data (with

quasi global coverage) are sought. This was also the reason of in-situ data to

characterize aerosol via optical (and microphysical) properties as those properties

are also derived from column remote sensing. Unfortunately, in-situ samples have

an upper size cut-off, the investigated aerosol is dried (water loss) and aerosol

properties at the ground often divert from aerosol for the entire column,

especially in cases of (advected) aerosol layers at higher altitudes. Thus even at

locations, where in-situ and ground remote sensing (usually the reference to

satellite remote sensing due to high accuracy) are co-located, matches for aerosol

composition (via co-single scattering albedo for absorption or asymmetry-factor

for size) are unlikely to match.

Aerosol compositions by in-situ optical sampling are statistically compared at

several ground sites to corresponding properties from remote sensing. The offsets

between both methods are at best qualitative similar. Quantitatively, statistical

offsets vary almost randomly by month and site. Unable to establish simple links

to aerosol optical properties from satellite data, the impact by in-situ aerosol

optical sampling to climate is at best limited. On the other hand regional air-

quality and health issues are nowdays of high(er) interest. And here in-situ data

can play an important role, especially when successfully tied to satellite remote

sensing that is sensitive to aerosol near surface properties.

P1.16 Pan-Eurasian experiment (PEEX) establishing a process towards high level pan-

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Eurasian atmosphere-ecosystem observation networks

H.K. Lappalainen, T. Petäjä ,N. Zaytseva, T.Laurila, G. De Leeuw, Y. Viisanen, V.

Kotlyakov, N. Kasimov, V. Bondur, G. Matvienko, Alexander Baklanov, Guo

Huadong, P. Hari, S. Zilitinkevich And M. Kulmala

Pan-Eurasian Experiment (PEEX) is a new multidisciplinary research approach

aiming at resolving the major uncertainties in the Earth system science and global

sustainability questions in the Arctic and boreal Pan-Eurasian regions and in China

(http://www.atm.helsinki.fi/peex/, Kulmala et al. 2011). PEEX initiative is built on

a bottom-up initiative by several European, Russian and Chinese research

organizations and institutes. The research program is aimed to solve the scientific

questions that are specifically important for the Northern Pan-Eurasian region in

particular the global climate change, its consequences to nature and Northern

societies. Pan-Eurasian region represents one the Earth most extensive areas of

boreal forest and the largest natural wetlands, thus being a significant source

area of trace gas emissions, biogenic aerosol particles, and source and sink area

for the greenhouse gas (GHG) exchange in a global scale (Guenther et al. 1995,

Timkovsky et al. 2010, Tunved et al. 2006, Glagolev et al. 2010). Furthermore,

PEEX is focused and the strategic and practical solutions for the improved air

quality in China megacities, the important sources of anthropogenic emissions in a

global scale.

The first implementation activities of the PEEX RI initiative is to establish a

process towards high level Pan-Eurasian Observation Networks. Siberian region is

currently lacking a coordinated, coherent ground based atmosphere-ecosystem

measurement network, which would be crucial component for observing and

predicting the effects of climate change in the Northern Pan-Eurasian region. The

first set of stations have been selected for the PEEX Observation network: the

SMEAR-type stations in Finland (SMEAR-I-II-II-IV stations), Estonia (SMEAR-

Järviselja) and China (SMEAR-Nanjing), 6-10 stations in Russia and four ecosystem

stations in China. The concept of the Pan-Eurasian network is based on a

hierarchical SMEAR-type (Stations Measuring Atmosphere-Ecosystem

Interactions) integrated land-atmosphere observation system (Hari et al. 2009).

The ground stations will have a minimum instrument setup and data processing

for atmospheric /forest / peat land/ aquatic / urban monitoring while the flag

ship stations will cover the full setup of instruments and data systems for

monitoring the energy flows in the land –atmosphere continuum. The ground

based observation setup would be completed by the remote sensing observations.

PEEX will bring the observation setup into international context with the

standardized or comparable procedures. Procedures for improved data quality

will be developed in coherence to “The European Strategy Forum on Research

Infrastructures” (ESFRI) process and in collaboration with the “Integrated Carbon

Observation System” research infrastructure (ICOS-RI), “Aerosols, Clouds, and

Trace gases Research InfraStructure Network” (EU-FP7-ACTRIS-I3 project),

“Analysis and Experimentation on Ecosystems” (EU-FP7- Preparatory Phase of

AnaEE), Life Watch (European research infrastructure on biodiversity) and

Svalbard Integrated Earth Observing System (SIOS).

REFERENCES

Glagolev M.V., Kleptsova I.E., Filippov I.V., Kazantsev V.S., Machida T. & Maksutov

Sh.Sh. 2010b. Methane Emissions from Subtaiga Mires of Western Siberia: The

“Standard Model” Bc5. Moscow University Soil Science Bulletin 65: 86--93.

15

Guenther A., Hewitt C.N. Erickson D., Fall R., Geron C., Graedel T., Harley P.,

Klinger L., Lerdau M., Mckay W.A., Pierce T., Scholes B., Steinbrecher R. Tallamraju

R., Taylor J. & Zimmerman P. 1995. A global model of natural volatile organic

compound emissions. J. Geophys. Res. 100: 8873--8892.

Hari, P., Andreae, M. O., Kabat, P. & Kulmala, M. 2009: A comprehensive network

of measuring stations to monitor climate change. Boreal Env. Res. 14: 442–446.

Kulmala M., Alekseychik P., Paramonov M., Laurila T., Asmi E., Arneth A.,

Zilitinkevich S. & Kerminen V.-M. (2011). On measurements of aerosol particles

and greenhouse gases in Siberia and future research needs. Boreal Env. Res. 16:

337-362.

Timkovsky I.I., Elanskii N.F., Skorkhod A.I. and Shumskii R.A. 2010. Studying of

biogenic volatile organic compounds in the atmosphere over Russia. Izvestiya

Atmospheric and Oceanic Physics 46: 319--327.

Tunved P., Hansson H.-C., Kerminen V.-M., Ström J., Dal Maso M., Lihavainen H.,

Viisanen Y., Aalto P.P., Komppula M. & Kulmala M. 2006. High natural aerosol

loading over boreal forests. Science 312: 261--263.

P1.17 Measurements at the Radiative Transfer Laboratory at the University of

Warsaw.

Krzysztof Markowicz, Iwona Stachlewska, Hanna Pawlowska

We present the Radiative Transfer Laboratory of the University of Warsaw - a

research infrastructure dedicated to measure aerosol optical properties their

impact on radiative equilibrium.

The main motivation for this study is a low degree of understanding of the

absorbing aerosol vertical distribution, as well as the climatology and the air mass

modification over Central-Eastern part of Europe. In this part of Europe the high

level of pollution due to a significant anthropogenic emission is accompanied by

large biomass burning activity in the Eastern Europe.

Our Radiative Transfer Laboratory includes two sites which are equipped with in-

situ and remote sensing instruments. The Research Station in Warsaw (52.212 N,

20.983 E, 110 m a.s.l. ) is localized in the city at the University’s campus. In-situ

observations of aerosol optical properties are affected by local emission from

traffic, and surrounding buildings. This site provides an opportunity to study the

impact of mega-city emissions on the columnar and surface optical properties.

The mean impact of the Warsaw's emission on the total AOD at 500 nm is about

0.02 (10-15%). The Research Site in Strzyzow (49.8786oN, 21.8613oE, 443 m

a.s.l.) is localized in South-Eastern part of Poland at the top one of the Carpathian

Mountains peaks and thus represents rural atmospheric conditions. Significant

distance from pollution sources (25 km from the largest city - Rzeszow) facilitates

representative studies for a wide geographic area. The station in Strzyzow is used

as a reference site for remote sensing and in-situ observations of the aerosol

interaction with its impact on the radiation budget. Strzyzow is located in the area

where there is a lack of experimental facilities dedicated to atmospheric research

in this part of Europe. Since Aug 2013 this site is also in the AERONET network.

Infrastructure of the University of Warsaw includes active remote sensing

16

instruments (eight channels PollyXT lidar, CHM15K Ceilometer), passive devices

(CIMEL, Microtops, MFR-7 sun photometers), solar and infrared radiometers,

aerosol in-situ optical instruments (micro-AE51 and AE31 aethalometer, Aurora

polar nephelometer, Photoacoustic Extinctiometers) as well as other instruments

for measurements of the surface weather condition, for launching radiosoundes,

and a small UAV to do vertical profiles of black carbon concentration in the lower

atmosphere. Instruments listed previously are easily transported from one station

to the other. Data collected at both stations are preprocessing and visualizing

within the Poland-AOD network at webpage www.polandaod.pl.

Wednesday, 11 June, 09:00 – 10:00

09:00-10:00 ACTRIS-2

Presentation of the project & discussion (part I)

G. Pappalardo / P. Laj

Oral session S2: Scientific results from ACTRIS TNA campaigns

Wednesday, 11 June, 10:00 – 12:00

Chairs: Adolfo Comerón, Sabine Philippin

S2.O1 (10:00-10:15) IDEAL-DREAM: integration of EARLINET/ACTRIS lidar observations and DREAM

dust model

L. Mona, A. Vukovic, I. Binietoglou, M. Vujadinovic, S. Nickovic3, G. Pejanovic, B.

Cvetkovic, M. Djordjevic, G. D’Amico, F. Madonna, N. Papagiannopoulos, M.

Rosoldi, G. Pappalardo

Passive ground-based (e.g., AERONET) or space-borne observations (e.g. MODIS,

MISR or OMI) have been extensively used to evaluate the 2D distribution of

particles, however the vertical distribution cannot be evaluated using these

observations. The vertical distribution of aerosol is of particular importance

because it is a combined signature of atmospheric transport patterns, residence

times in the atmosphere, and the efficiency of the vertical exchange. Lidar

techniques provides information about aerosol layering in the vertical range and

vertical profiles of aerosol optical properties.

A systematic long-term comparison of dust profiles from EARLINET stations and

the coupled atmospheric-dust model NMM-DREAM is performed for evaluating

the model vertical profiling capability. The most recent DREAM version, which

runs operationally at SEEVCCC of the Serbian Hydrometeorological Service, is used

for historical long-term simulations.

This model version also includes, in addition to dust concentration as a tracer,

fractions of major mineral groups’ characteristic for specific Saharan desert parts

(East-West), as well (Nickovic et al, 2012; Nickovic et l, 2013). These modeled

data are used for the evaluation and integration to EARLINET data. Therefore, for

selected cases with increased dust transport from Sahara to Europe, and

available lidar observations, special modeling tests will be done. Lidar data will be

assimilated into the dust concentration initial field for the dust forecast, and the

quality of forecast will be compared with regular model set-up.

The TNA access to CIAO started the collaboration between DREAM modeling

group from Belgrade and CIAO lidar group from Potenza, and enabled future

work on improving quality of dust forecast using lidar observations. Further

analysis about lidar data assimilation and ice nucleation in presence of Saharan

17

dust events will be carried out.

S2.O2 (10:15-10:30) Study of aerosol hygroscopic growth events over the CESAR (Cabauw

Experimental Site for Atmospheric Research) station by means of the Caeli lidar

A. J. Fernández, A. Apituley, F. Molero, M. Pujadas, B. Artíñano, J. Henzing and H.

Russchenberg

According to the Fifth Assessment Report (AR5) of the IPCC (2013), atmospheric

aerosols still represent the largest source of uncertainty in the total radiative

forcing estimates of the atmosphere, in particular concerning the influence of

aerosols on cloud formation processes. The so-called cloud adjustments due to

aerosols is quantified in -0.55 W m-2 (-1.33 to -0.06). Since multiwavelength

Raman lidars have the potential to provide aerosol optical properties, water

vapor mixing ratio and temperature profiles (depending on its configuration) with

high resolution in time and vertical dimensions, lidar techniques represent a

powerful tool to study these phenomena. Given the fact that Caeli (the CESAR

Water Vapour, Aerosol and Cloud lidar), deployed since 2008 at the Cabauw

Experimental Site for Atmospheric Research (CESAR) in the Netherlands (51º 58’N,

4º56’E), has been routinely performed for EARLINET purposes, the project ACIRL

(Aerosol Cloud Interaction and Raman Lidar), which has been carried out under a

Transnational Access Activity from ACTRIS, was partially devoted to identify

aerosol hygroscopic growth events from the Caeli lidar database and analyze

them thoroughly. The primary objective of this analysis is to characterize the

enhancement factor experienced by the hygroscopic aerosol throughout the

atmospheric column placed over the CESAR station. Other optical properties such

as lidar ratio and β- Ångström exponent are also considered in the case studies

that will be presented as they can be used as tracers when the water uptake

phenomenon takes place. Additionally, meteorological information is taken into

account in order to check that a well-mixed boundary layer exists and therefore

misleading results are avoided. Acknowledgments: The research leading to these

results has received funding from the EU 7th Framework Programme (ACTRIS

project, grant agreement nº 262254, and TNAs) and from the MICINN (Spanish

Ministry of Science and Innovation) under project CGL2010-17777.

10:30-11:00 Coffee break

S2.O3 (11:00-11:15) The Fourier-Transform Infrared Measurements at Maïdo and the Results of the

ACTRIS TNA Missions

F. Desmet, B. Langerock, C. Vigouroux, N. Kumps, C. Hermans, M. De Mazière, J.-

M. Metzger, J.-P. Cammas

The Belgian Institute for Space Aeronomy (BIRA-IASB) has been performing FTIR

measurements at Reunion Island since 2002, initially as part of short-term

campaigns, but since 2009 on a permanent basis. The FTIR instruments record

solar-absorption spectra of the atmosphere, from which the total column

abundance and vertical distribution of a wide variety of atmospheric species can

be retrieved. BIRA-IASB currently operates two spectrometers on the Island, one

at sea-level in St. Denis and a second instrument in the Maïdo observatory. Part

of the installation of the instrument at Maïdo and related scientific work has been

supported by ACTRIS TNA grants. The FTIR instrument on Maïdo began its

measurements in March 2013, it contributes data principally to the Network for

the Detection of Atmospheric Composition Change (NDACC).

In this presentation, we give an overview of the FTIR instruments at Reunion

18

Island. We look at the benefits of the high-altitude location of Maïdo, and the

effects of the reduced interference of water vapour on the spectra and the

retrievals. We will also report our preliminary results of how the 2 km altitude

difference between Maïdo and St. Denis affects the results of the retrievals.

S2.O4 (11:15-11:30) AERONET-EUROPE TNA

P. Goloub, V. Cachorro, E. Cuevas, C. Toledano, L. Blarel, T. Podvin, R. González, C.

Guirado, A. Lapyonak

AERONET-EUROPE Trans National Access has provided, since the beginning of

ACTRIS, calibration, maintenance and technical support to CIMEL sunphotometers

belonging to various European research teams and other groups in Africa and

Asia involved in aerosols studies. This activity relies on France (LOA) and Spain

(GOA and Izaña-AEMET). We will present the main contributions and projects

supported during the second period such as number of access unit provided,

quality assurance, contribution to satellite and models evaluations, impact on the

development of synergetic use of LIDAR and sun/lunar photometer, impacts on

SMEs developments.

S2.O5 (11:30-11:45)

A source origin and physico-chemical properties of ambient Particulate Matter

studied by Stable Isotope Ratio Mass Spectrometry

A. Masalaite, D. Ceburnis, J. Ovadnevaite, V. Remeikis and C.D. O’Dowd

Carbonaceous aerosols reflect the isotope signature of their source precursors

(e.g., biogenic marine, terrestrial and fossil fuel carbon) and, consequently, their

δ13C value can be used as an indicator of the specific source. Similarly, isotopes

of sulphur and nitrogen can help to further apportion between biogenic and

anthropogenic sources.Combining the knowledge of marine aerosol properties

through the use of advanced High Resolution Time-of-Flight aerosol mass

spectrometer (AMS) with stable Isotope Ratio Mass Spectrometry (IRMS) provide

unique insight into particulate matter sources, especially when applying multi-

isotope (S, N, C) approach. High time resolution of AMS allows quantifying total

amount of carbonaceous or sulphurous components in uniquely classified marine

air masses: marine polar, marine tropical and marine arctic. Active sector control

sampling system allows apportionment of sources in the above air mass

categories by IRMS. The sampling in carefully screened marine air masses has

been initiated during an ACTRIS TNA visit and is still continuing. A method

development for multi-isotope analysis is on-going. A split between total carbon

and organic carbon δ13C in marine aerosol samples has been attempted for the

first time. The obtained results so far reaffirm previously published results of

marine carbonaceous matter enriched in heavier isotope. Parallel sampling of

size-segregated particulate matter at various locations in Lithuania helped to

further develop stable carbon isotope method in distinguishing between fossil fuel

and terrestrial source without the need of radiocarbon analysis. The samples

obtained during ACTRIS TNA visit will help to better interpret the results from

marine location in Lithuania which is significantly affected by anthropogenic

emissions en-route from the North Atlantic Ocean.

S2.O6 (11:45-12:00) Nitrogen intensive at Auchencorth Moss: Basis for study and first insights

M.M. Twigg, J. Kentisbeer, M. Coyle, S.R. Leeson, Y.S. Tang, M.R. Jones, B.

Langford, C. DiMarco, I. Simmons, I. Washbourne, M. Vieno, C.F. Braban, E.

Nemitz,W. Bloss, E. Aruffo, P. Di Carlo

19

Auchencorth Moss has been an EMEP supersite since June 2006, where currently

routinely speciated N measurements are: HNO3, NO2, NO, HONO, NH3 in gas

phase and particulate NH4+ and NO3-. It is understood that the full speciated N-

budget is currently unknown and recent studies have shown the importance of

chemical species such as trimethlyamines, PANs, ClNO2 and N2O5 at background

sites. In order to better understand the chemical climate at Auchencorth and in

particular quantify the N-speciation in the atmosphere over time and the co-

variation of non-routinely measured species against the rountine measurement,

CEH are hosting an intensive experiment to monitor nitrogen chemical speciation

over the Spring 2014 season. The spring has been chosen as the data records

show that the site frequently experiences pollution events from agricultural

activities and long range transport from continental Europe during this period.

As well as the routine measurements at Auchencorth Moss, VOC fluxes by PTRMS

and fluxes of water soluble aerosols and their precursor gases using a GRAEGOR,

the Thermal Dissociation Laser Induced Fluorescence (TD-LIF) instrument from the

Univeristy L’Aquila is deployed for simultaneous measurements of NO2, total

peroxy nitrates (∑RO2NO2, ∑PNs), total alkyl nitrates (∑RONO2, ∑ANs) and

NOy/HNO3 ,a LOPAP for HONO and a cavity ring down instrument for NH3 are

deployed to be operational through May and June 2014. The TD-LIF, in parallel

with the other systems installed at the Auchencorth moss Supersite can

contribute to understand the nitrogen oxides chemistry of the lower troposphere

and potentially quantify the budget of NOy of this site.

Poster session P2: Scientific results from ACTRIS TNA campaigns

Wednesday, 11 June, 10:30 – 11:00 and 12:00 – 12:30

P2.1 Side-by-side Intercomparison for OVOC in the framework of ACTRIS NA4

J. Englert, C. Plass-Dülmer, A. Werner and ACTRIS partners

Oxygenated volatile organic compounds are difficult to measure in atmospheric

samples due to their low mixing ratios in the low ppt to ppb range, their polarity

and associated stickiness to surfaces, and their partly high water solubility. Thus,

it is not amazing that occasionally colocated instruments with “similar”

measurement technique obtain considerably different results. With focus on high-

quality measurements, the need of a better characterisation of measurement

techniques has been identified in GAW VOC Expert meetings. This has been

addressed in the tasks of work package NA4 (Trace gases networking: Volatile

organic carbon and nitrogen oxides).

Seven groups with ten different state-of-the-art OVOC instruments (PTR-MS,

GC/MS/FID, adsorbent tube sampler and DNPH cartridges) joined in a combined

field and laboratory intercomparison exercise at the Hohenpeissenberg

Meteorological Observatory in October 2013. All instruments were connected to a

single manifold which was fed with synthetic air mixtures, zero air, pure and

spiked ambient air at controlled ozone and humidity levels. Three of the

participating groups performed TNA projects and received T&S support by

ACTRIS.

Compared to a previous intercomparison at the SAPHIR chamber in Juelich (Apel

et al., 2008), the Hohenpeissenberg OVOC intercomparison expanded the range

20

of tested mixing ratios down to the low ppt range and included synthetic and

ambient air at OVOC mixing ratios of mostly below 1 ppb, for many compounds

even below 100 ppt. Thus, it comprised a test of the instruments under typical

clean air conditions encountered at the stations of the monitoring networks of

GAW and EMEP and enables a full characterization of the detection limits, linear

ranges, and of potential artefacts due to interfering gases.

A first look at the mixing ratios obtained during the campaign indicates both

consistent results between different instruments albeit using different techniques,

and partly clear deviations of individual or groups of instruments. These

deviations are further analysed with respect to reference concentrations,

characteristics of the respective techniques, blank and calibration issues and

uncertainties. Apel, E. C. et al. (2008) Intercomparison of oxygenated volatile

compound measurements at the SAPHIR atmosphere simulation chamber, J.

Geophys. Res., 113, D20307, doi:10.1029/2008JD009865.

P2.2 Experimental assessment of the lidar polarizing sensitivity in lidar

depolarization studies for aerosol typing

Belegante L., Bravo-Aranda J. A., Freudenthaler V., Nicolae D., Alados-Arboledas

A., Amodeo A., Engelmann R., Kokkalis P., Papayannis A., and Wandinger U.

Profiles of the particle depolarization ratios retrieved from lidar data are

generally used for aerosol typing, accounting for the non-sphericity of the

particles. The particle depolarization ratio is one of the primary parameters that

can differentiate several major aerosol components, but for this the associated

uncertainties have to be sufficiently reasonable and correctly assessed. The paper

presents an extended analysis of different depolarization calibration procedures

and experimental procedures aiming to correct for the contribution of several

optical modules in the depolarization values. All procedures are specific to the

requirements of each lidar systems in the EARLINET framework, aiming to better

quantify the particle depolarization ratio. The results illustrate a significant

improvement of the depolarization lidar products for all selected lidar stations in

the network. The calibrated particle depolarization profiles show values reaching

up to 0.45±0.02 in ice crystals, 0.3±0.02 for aged dust and 0.05±0.01 for industrial

pollution aerosol. In the aerosol free regions, the particle depolarization ratio

goes down to 0.00.

Keywords: Atmospheric studies, Aerosol typing, EARLINET, depolarization

calibration, particle depolarization ratio

Acknowledgements: This work was supported by the European Community's FP7-

INFRASTRUCTURES-2010-1 under grant no. 262254 – ACTRIS and by a grant of

the STAR–ESA Programme 39/2012-SIAFIM.

P2.3 Size-dependent particle activation properties in fog during the ParisFog

2012/13 field campaign

E. Hammer, M. Gysel, G. C. Roberts, T. Elias, J. Hofer, C. R. Hoyle, N. Bukowiecki,

J.-C. Dupont, F. Burnet, U. Baltensperger and E. Weingartner

A custom built (TROPOS type) scanning mobility particle sizer (SMPS) was used

covering size ranges from 8 to 848 nm. Throughout the measuring period the

median number concentration of aerosol particles (total) was found to be 2098±

1332 cm -3. A clear annual circle with maximum concentrations during summer

and minimum during winter was observed. Both Aitken and accumulation mode

21

particles presented similar seasonality and contributed equally to the total

number. Nucleation mode presented different pattern from the other two modes,

with the highest concentrations during winter (and March), mainly during new

particle formation events that were more frequently observed during March and

October. During summer, new particle formation events were less frequent and

unimodal distributions centering in the accumulation mode size range were

dominant reflecting the dry season characteristics. When precipitation had

affected air masses arriving at Finokalia, the size distributions were bimodal,

typical for marine origin, and representative of the background marine conditions

at Finokalia.

P2.4 Ceilometer for aerosol profiling: comparison with the multiwavelength in the

frame of INTERACT (INTERcomparison of Aerosol and Cloud Tracking)

F. Madonna, J. Vande Hey, F. Amato, M. Rosoldi, G. Pappalardo.

Observations of cloud base height are important for meteorology, observations of

aerosols are important for air quality applications, observations of cloud cover

and aerosols address key uncertainties in climate study. To improve

parameterization and uncertainties of numerical models, observations provided

by high resolution networks of ground-based instruments are needed. In order to

achieve broad, high resolution coverage, low-cost instruments are preferable,

though it is essential that the sensitivity, stability, biases and uncertainties of

these instruments are well-understood.

Despite of their differences from more advanced and more powerful lidars, low

construction and operation cost of ceilometer, originally designed for cloud base

height monitoring, has fostered their use for the quantitative study of aerosol

properties. The large number of ceilometers available worldwide represent a

strong motivation to investigate to which extent they can be used to fill the

geographical gaps between advanced lidar stations and how their continuous

data flow can be linked to existing networks of the advanced lidars, like EARLINET

(European Aerosol research LIdar NETwork).

In order to make the best use of existing and future ceilometer deployments,

ceilometer must be better characterized. This is the purpose of the INTERACT

campaign carried out in the frame of ACTRIS Transnational Access activities at

CNR-IMAA Atmospheric Observatory (CIAO - 760 m a.s.l., 40.60 N, 15.72 E).

The scientific objectives of INTERACT are to evaluate the stability, sensitivity, and

uncertainties of ceilometer aerosol backscatter profiles and to evaluate the

sensitivity, uncertainties, and idiosyncrasies of ceilometer automated cloud base

detection. In the frame of INTERACT, for the first time, three commercial

ceilometers from different manufactures have been compared with an advanced

Raman lidar.

INTERACT data collection began officially on 1 July, 2013 and ended on 10

January, 2014. The ceilometers run 24-7, reporting at least once per minute.

Multi-wavelength Raman lidar measurements performed at CIAO Atmospheric

Observatory (760 m a.s.l., 40.60 N, 15.72 E), performed on a systematic basis (at

least four times a week) have been used to investigate the capability of

ceilometers to provide reliable information about the atmospheric aerosol

content.

The study of the attenuated backscattering values as a function of both the

altitude and the 355 nm aerosol extinction coefficient (α), provided by the multi-

wavelength Raman lidar, reveals a few limitations both in the ceilometer

22

experimental setup and in the achieved SNR. Further technological improvements

of the ceilometers towards their operational use in the monitoring of the

atmospheric aerosol looks mandatory.

P2.5 ACTRIS Trans National Activities at the SIRTA Atmospheric Observatory (2011-

2014)

M. Haeffelin, J-C. Dupont, C. Pietras; J. Sciare, V. Gros

The SIRTA observatory gathers an ensemble of state-of-the-art in-situ and active

and passive remote sensing instruments deployed by several French research

laboratories since 2002 for cloud, aerosol and trace gas research. In the 2011-

2014 timeframe, SIRTA hosted 5 transnational activity projects in the framework

of ACTRIS, providing a total of 260 access days. Four TNA project took place in the

framework of international field campaigns organized at the SIRTA observatory,

providing both mobility of experts and training benefits. The fifth project was

hosted to provide training benefits. Project 1 (2011) focused on comparison of OH

and OH reactivity measurements made with different techniques. 37 ACTRIS TNA

access days were provided to 3 users, while 140 other access days were also

provided to 5 other user groups during the same campaign. Projects 2 and 3

(2012-2013) were organized as part of the ParisFog international field

experiment. The ParisFog campaign gathered 6 user groups over a period of 6

months from October 2012 to March 2013. Project 2 focused on understanding

aerosol activation during radiative fog events under moderately polluted

conditions (50 access days, 2 users incl. 1 PhD student). Project 3 aimed at better

characterizing turbulent fluxes of fog droplets/liquid water by using the eddy

covariance techniques (138 access days, 4 users incl. 2 PhD students). Both TNA

projects resulted in scientific publications. Project 4 took place in the framework

of an ACTRIS international Aerosol Chemical Speciation Monitor intercomparison

campaign (8 access days, 1 user). The campaign gathered 14 user groups during 3

weeks in November 2013. Project 5 will allow two users from Bulgaria, including 1

PhD student, to conduct a study on aerosols and turbulence as tracers of the

diurnal evolution of boundary layer height. It will take place in May 2014. Results

from the 5 projects will be presented, and highlights from other non-ACTRIS user

accesses to the facility will also be provided.

P2.6 QA /QC of European NOx measurements by round robin and side by side

experiment at the Meteorological Observatory Hohenpeissenberg in the

framework of ACTRIS

Stefan Gilge, Christian Plass-Duelmer, Dietmar Weyrauch, Franz Rohrer and the

ACTRIS-NOx-Team.

The European ACTRIS (Aerosols, Clouds, and Trace gases Research InfraStructure

Network) project, Work Package 4, aims at harmonization and improvement of

the measurement of volatile organic carbons and nitrogen oxides. Central tools to

assess and compare the performance of monitoring stations and labs within

ACTRIS are a round robin experiment (2012) and side-by-side intercomparisons

(Nov 2012). While the first checked the used laboratories’ scales versus a common

scale, the latter investigated weather same samples are identically and artefact-

free analyzed by collocated instruments. The ACTRIS-NOx-side-by-side

intercomparison was realised by instruments sampling from a common manifold

which was fed by zero gas, synthetic air mixtures, ambient air, and spiked

ambient air. Thus, the side-by-side experiments enabled a full characterization of

23

the detection limit, the linear range, the span, and of potential artefacts due to

interfering species for each of the contributing instrument. Generally, CLD type

NOx instruments were used in the comparisons supplemented by four new optical

techniques, comprising LIF and cavity enhanced techniques. In the round robin

exercise, some 20 monitoring sites participated, and 14 instruments were running

side-by-side in the one week Nov comparison. The results of both experiments will

be presented and discussed with respect to the data quality objectives of GAW

and ACTRIS.

P2.7 Feedbacks between Turbulent Fluxes of Heat, Water Vapor and Liquid Water

and Droplet Microphysics in the evolution of Radiation fog at SIRTA, France

Degefie Tibebe, Otto Klemm, Tarek El-Madany and Jean-Charles Dupont

The interaction between fog microphysical properties and turbulent fluxes of fog

droplets (liquid water), water vapor, and energy was studied based on the

measurement made during the PARISFOG campaign in winter 2012/2013 at the

SIRTA (Site Instrumental de Recherche par Télédétection Atmosphérique)

atmospheric observatory near Paris. The measurement was undertaken using the

eddy covariance technique employing a fast (10 Hz) fog droplet spectrometer, a

three-dimensional ultrasonic anemometer, and a fast response gas analyzer,

which were operated at an altitude of 2.5 m above ground. Additionally, a

visibility meter was used to detect the occurrence and density of fog. In this study,

a detailed analysis was made on one of the radiation fog events which happened

on November 8-9, 2012. In the evolution of the fog event, the feedbacks between

the microphysical properties and the turbulent fluxes of fog droplets (liquid

water), water vapor and energy was examined with the combined reasoning of

microphysical processes like condensation, collision–coalescence, and droplet

evaporation. Both upward and downward droplet number fluxes and liquid water

fluxes were observed depending on the position at which the microphysical

process occurred with respect to the measurement height. The downward water

vapor fluxes were the major cause for (I) the broadening of the fog droplet size

distribution and (II) the largest upward fog water fluxes throughout the whole

event.

P2.8 Understanding aerosols as tracers of boundary layer development and

turbulence mixing processes

M. Haeffelin, J-C. Dupont, (IPSL/CNRS); E. Batchvarova, O. Gueorguiev (NIMH); S.

Pal (U. of Virginia); N. Cimini (CNR-IMAA)

The development of the boundary layer in convective conditions, and the depth of

the layer in which surface emitted constituents are mixed, must be well

understood to relate fluxes and concentrations. Air pollution and greenhouse gas

communities are interested in precisely tracing the mixing depth to improve

predictions of atmospheric constituents such as fine-mode aerosols or CO2.

Vertical profiles of several tracers and parameters can be used to define the

mixing layer depth, such as the potential temperature, water vapor mixing ratio,

wind variance, aerosol concentration or extinction coefficient. Retrieving the

mixing depth then requires instruments that can provide vertical profiles of these

parameters, preferably several times per day to cover mixing depth variations in

the diurnal timescale. Well-known candidates are aerosol backscatter profiles

from ground-based lidars, vertical velocity variance profiles from Doppler lidar,

potential temperature profiles from microwave radiometers (MWRs) and

24

radiosondes, temperature turbulence profiles from sodars.

In this presentation we will focus on analyses of discrepancies of mixing height

retrievals from aerosol backscatter Lidar, wind variance from Doppler Lidar and

temperature profiles from microwave radiometers. We will aim at identifying and

describing physical processes that can explain discrepancies between retrievals

based on aerosol profiles and those based on potential temperature profiles and

wind velocity variance.

12:30-14:00 Lunch break

Oral session S3: ACTRIS integration activities

Wednesday, 11 June, 14:00-17:00

Chairs: Philippe Goloub, Markku Kulmala

Keynote presentation

(14:00-14:30)

Aerosol_CCI validation experiences

Thomas Holzer-Popp (DLR, Germany)

S3.O1 (14:30-14:45) Aerosol typing based on 24/7 measurements with EARLINET multi-wavelength-depolarization lidars in analogy to Cloudnet H. Baars, P. Seifert, F. Schneider, R. Engelmann, and U. Wandinger

An automatic technique for the classification of different aerosol types from

EARLINET measurements was developed in the frame of ACTRIS. This

development is a synergistic approach to the Cloudnet cloud classification scheme

which makes use of ceilometer, radar, and microwave radiometer but provides no

sophisticated aerosol information. The new retrieval scheme is based on

continuous observations with multi-wavelength-depolarization Raman lidars.

Developments within EARLINET/ACTRIS concerning quality assurance and

calibration made it possible to develop hardware tools to run the lidar systems

quality-controlled in a 24/7 mode.

In this contribution, the procedure for aerosol retrievals is described in terms of

hard- and software for the example of the PollyXT lidar which is operated by

TROPOS, Leipzig, Germany. For the particle classification, the backscatter profiles

at three wavelengths are used to detect aerosol and cloud layers and to

distinguish between those two. Simple thresholds are used to separate liquid

clouds from other features. For aerosol and ice clouds, the classification is much

more sophisticated and makes use of the intensive particle properties. For this

purpose, the Ångström exponent is used as a rough measure of the particle size

and the depolarization ratio is used to determine the particle shape. The

knowledge gathered from the long-term observations within EARLINET is finally

applied for the target classification which distinguishes between the following

features: clean atmosphere (no particles); small aerosol particles (e.g., urban

pollution); large, spherical aerosol particles (e.g., marine); aerosol mixture (partly

non-spherical particles, e.g., polluted dust); large non-spherical particles (e.g.,

dust or volcanic ash); non-typed particles; ice clouds; liquid clouds; and non-typed

clouds.

In this contribution, examples of the typing from PollyXT measurements will be

shown and compared to the corresponding Cloudnet classification. For future

25

applications, the combination of this lidar stand-alone retrieval with the Cloudnet

target categorization will be discussed to make full use of the synergy of the

available instruments.

S3.O2 (14:45-15:00) Framework for monitoring aerosol-cloud interactions K. Sarna and H.W.J. Russchenberg

A broad range of strategies have been used to study the first aerosol indirect

effect [2]. However, the wide scope of methods and scales used makes it difficult

to quantitatively compare result from different studies. We propose a new

approach for aerosol-cloud interaction (ACI) observations, which will provide a

fast and easily applicable way of identifying cases where a change in the aerosol

environment causes a change in the cloud. In this scheme we attempt to use (as

far as possible) the observed signal from lidar and radar, in order to bypass

the complexity and uncertainty associated with different retrieval techniques.

We propose to use the attenuated backscatter as an aerosol proxy and the radar

reflectivity factor combined with the extinction coefficient at the cloud base to

obtain information about changes in the cloud. To retrieve the extinction

coefficient we use a stable lidar profile inversion [1] with a correction for multiple

scattering effects. Together with radar reflectivity the extinction coefficient is

used to estimate the size of cloud droplets in the lower part of the cloud only. To

eliminate other factors that can change microphysical properties of the cloud we

put a constraint on the liquid water path. Although this method is based on a

synergy of remote sensing instruments, we use widely available systems for a

quick and efficient evaluation of the aerosol influence on the cloud. The main

advantages of this scheme include fast data processing and a possibility of easy

application at new or existing observational sites. Moreover, this approach

enables processing large time series of data and is less restrictive in cases

selection tan most microphysical cloud properties retrieval algorithms. We plan to

implement this framework over the cloud profiling sites of the ACTRIS network to

enable monitoring of the ACI close to real-time.

References

[1] Klett, J. D. Stable analytical inversion solution for processing lidar returns.

Appl. Opt. 20, 2 (Jan. 1981),

211–220.

[2] McComiskey, A., and Feingold, G. T

S3.O3 (15:00-15:15) On scientific breakthroughs from ACTRIS observations and on integration of ACTRIS observation components

T. Petäjä et al. + ACTRIS partners + BAECC partners + PEEX partners

Recent technological advances in aerosol measurement techniques have enabled

comprehensive analysis of chemical and physical characterization of atmospheric

nanoparticles. For example, we have underlined the importance of sulfuric acid,

bases and extremely low volatile organics to the initial clustering as well as to

aerosol growth to climatically relevant sizes (Sipilä et al. 2010, Almeida et al.

2013, Kulmala et al. 2013, Ehn et al. 2013, Riccobono et al. 2014). Within the

harmonized ACTRIS observation network we have been able put the observations

in a larger context via campaigns, partly supported by transnational access e.g. to

Hyytiälä, Jungfraujoch and Mace Head.

Co-located observations of in-situ and active remote sensing in campaigns such as

26

"Biogenic Aerosols- Effects on Clouds and Climate, BAECC" in Hyytiälä will provide

essential instrumental and methodological intercomparison as well as possibilities

for various closure studies, which are also the focus of BACCHUS project. The joint

campaign with AMF2 in BAECC as well as Pan Eurasian Experiment (PEEX) provide

extension of integrated ACTRIS data products beyond Europe.

S3.O4 (15:15-15:30) Results of the first-ever ACSM intercomparison study from the ACTRIS-ACSM network V. Crenn, J. Sciare, O. Favez, P. L. Croteau, R. Fröhlich, A. Setyan, S. Verlhac, V. Riffault, M. Äijälä, M. Bressi, C. Carbone, F. Cavalli, E. Coz, M. J. Cubison, J. K. Gietl, L. Heikkinen, C. Lunder, M. C. Minguillón, J. Ovadnevaite, E. Petralia, L. Poulain, M. Priestman, A. Ripoll, B. Artíñano, D. Baisnée, N. Bonnaire, M. Canagaratna, D. C. Green, G. Mocnik, V. Gros, J.-E. Petit, R. Sarda-Estève, J. T. Jayne, and A. S. H. Prévôt

As part of the EU-FP7 ACTRIS program, a large international intercomparison

study of 15 aerosol mass spectrometers (13 Q-ACSM, 1 ToF-ACSM and 1 HR-ToF-

AMS) has been performed from 15 Nov. to 2 Dec. 2013 at the LSCE in-situ

atmospheric platform which is part of the French SIRTA observatory

(http://sirta.ipsl.fr) located at 20km southwest of Paris. During this period, each

instrument measured the major non-refractory submicron aerosols (NR-PM1)

components (organic matter, nitrate, sulfate, and ammonium) in ambient air.

The accuracy of Q-ACSM instruments was determined by comparison with various

co-located instruments (TEOM-FDMS, SMPS, OPC, OC-EC Sunset Field analyzer,

PILS-IC, aethalometers, nephelometers, and filter sampling). The measurement

precision was also evaluated by intercomparing the correlation of absolute mass

concentrations for all the NR-PM1 species. The ACSM analytical uncertainties

were then estimated by applying a statistical approach in order to evaluate the

analytical standard deviations between ACSMs and to highlight any bias or

influencing factor on the ACSM measurements. For this purpose, the Z-score

indicator representing performance criteria was used making it possible to

measure its relative deviation to the assigned value. Fig. 1 summarizes the Z-

Score results applied to the 13 Q-ACSM datasets for the major chemical species of

the NR-PM1. All the ACSMs present satisfactory Z-Score values (a Z-Score value of

3 is considered as the limit value) whatever the considered parameter

highlighting the instrument precision.

Figure 1: Statistical Z-Score results for total NR-PM1

concentrations and their major components measured by

the 13 Q-ACSMs.

15:30-16:00 Coffee break

S3.O5 (16:00-16:15) Co-located station Košetice (ACTRIS) – Křešín u Pacova (ICOS) M. Váňa and A. Dvorská

The co-located station (geographical co-ordinates: 49°35´ N; 15°05´E; 534 m

a.s.l.) is formed by Košetice Observatory (operated by the Czech

Hydrometeorological Institute) and 250 m high atmospheric mast (operated by

Global Change Research Centre, Academy of Sciences of the Czech Republic). The

Observatory was established in 1988 as a background station specialized in air

quality monitoring and research and represents Czech Republic in long-term

activities under CLRTAP (EMEP, ICP-IM) and WMO (GAW). Tall tower was opened

in 2013. The most important research and monitoring activities include long-term

27

measurement of greenhouse gases concentrations and their exchange dynamics

under the ICOS project. The tower is also used for investigating the impacts of

global climate change on air quality and long-range transport of air pollution. The

research will be focused on pollutants with a high potential for hemispheric

transport (tropospheric ozone, aerosols and mercury). Besides ICOS and ACTRIS,

co-located station is involved in other EU projects (InGOS, GMOS). Special

attention is devoted to atmospheric aerosols which have besides greenhouse

gases an important impact on global climate change processes. The integration of

ACTRIS and ICOS activities at the core stations is in line with the ACTRIS objectives

for Integration, Outreach and Sustainability (NA6). Co-located ACTRIS – ICOS

station Košetice has very good potential for successful participation in the pan-

European Research Infrastructures (RIs) under ESFRI and other projects covering

both climate and air quality issues. Moreover, monitoring and research activities

within ACTRIS and ICOS will bring essential improvement for the Czech

partnership in long-term monitoring programmes (EMEP, GAW).

S3.O6 (16:15-16:30) Advanced Analysis of Atmospheric Processes and Feedbacks and Atmosphere-Biosphere Interactions

Markku Kulmala

Quantification of feedbacks and relationships between atmosphere and biosphere

using a variety of relevant datasets from several measurement stations. Results

from ACTRIS winter school, Hyytiälä 2014

S3.O7 (16:30-16:45) ACTRIS Data Centre: Description and demonstrations by active user participation Cathrine Lund Myhre, Thomas Hamburger, Robert Logna, Markus Fiebig, Aasmund Fahre Vik Holger Linné, Ewan O'Connor, Kjetil Tørseth

The ACTRIS data centre (ACTRIS DC) provides free and open access to all

measurement data resulting from the ACTRIS infrastructure. This includes

currently measurements from more than 50 sites and of approximately 120

different atmospheric variables, 90 different trace gases, 10 aerosol in situ

variables, 10 aerosols profile variables, and 8 cloud variables. After careful and

systematic quality assurance, all observational data are archived in three

specified databases, depending on measurement type and methodology. The

ACTRIS data portal links these databases and provides joint overview and access

to all ACTRIS data from one location (http://actris.nilu.no/). The ACTRIS data

portal is complemented with data from other relevant networks and databases,

and allows users to search for atmospheric composition data from a multitude of

data archives through a single user interface. Some of the included frameworks

are EMEP, the GAW- world data centres, EARLINET, NDACC, and AMAP. All data

from e.g. EMEP and NDACC can be downloaded through the ACTRIS data portal.

The portal is currently under revision, and new functionality gets implemented

during spring 2014. This development includes an improved user interface,

plotting functionality for comparing and integrating data across various ACTRIS

activities, improved interface to AEROCOM, access to ACTRIS Standard Operating

Procedures (SOPs), and improvement of data format and meta data descriptions.

During the poster session at the 4th ACTRIS meeting we will demonstrate and

explain the ACTRIS data portal. We plan to set up PCs to actively involve ACTRIS

28

data users and partners, to assist and demonstrate the use of the ACTRIS data

portal. This activity will also facilitate the collection of feedback for final

adjustments within the ACTRIS project. Furthermore, we will provide an overview

of all sites delivering data to ACTRIS, and summarize the access to measurements

within the ACTRIS project.

S3.O8 (16:45-17:00) Proposal for the integration of ACTRIS Near-Real-Time NO2 data in the evaluation activities of the Copernicus Atmosphere Service (MACC-II) Annette Wagner, Harald Flentje, Stefan Gilge, Werner Thomas and the MACC Team

The MACC-II (Monitoring Atmospheric Composition and Climate- phase II) project

is the current pre-operational Atmosphere Service of the European earth

observation program Copernicus. MACC-II combines state-of-the-art atmospheric

modelling with earth observation data to provide information services covering

European air quality, global atmospheric composition, climate forcing, the ozone

layer, UV and solar energy, emissions and surface fluxes in Near-Real-Time. The

sub group “VAL” of the MACC-II project is focusing on the evaluation of modelled

reactive gases, such as stratospheric and tropospheric ozone as well as its

precursors and aerosols in the global ECMWF integrated forecasting system IFS.

Currently, GAW NRT data of 13 stations is used to validate modelled O3 and CO

surface mixing ratios globally. Additionally, ozone sonde data of the NDACC,

WOUDC, NILU and SHADOZ networks enable a validation of O3 profiles.

Here, we will give an overview on the Near-Real-Time (NRT) evaluation activities

in MACC and an outlook on a potential use of ACTRIS NO2 NRT data in the

evaluation activities of the Copernicus Atmosphere Service.

17:00 Excursion to the Puy de Dôme and social dinner (return ~23:30)

Oral session S4: ACTRIS, Model and Satellite

Thursday, 12 June, 9:00 – 10:30

Chairs: Stefan Reimann, Ulla Wandinger

Keynote presentation

(9:00-9:30)

ICOS-ACTRIS Synergies Werner Kutsch (ICOS, EU)

S4.O1 (9:30-9:45) Aerosol-Cloud interactions over the Nordic countries

Moa Sporre, Erik Swietlicki, Paul Glantz and Markku Kulmala

One of the major uncertainties in predicting the future climate is aerosol-cloud

interactions. 10 years of satellite data of clouds from the MODIS (Moderate

Resolution Imaging Spectroradiometer) instrument has been combined with

ground-based aerosol measurements from two Nordic ACTRIS stations (Vavihill

and Hyytiälä). This is done to investigate how aerosols affect cloud properties of

convective and low-level clouds. Furthermore, to determine if precipitation is

affected by aerosol particle number concentrations, weather-radar data from the

Baltic Sea Experiment has been used. Reanalysis data from the European Centre

for Medium-Range Forecasts is also investigated to determine how

meteorological conditions affect the aerosol-cloud interactions. This study is an

example of how multiple long-term data sets are combined to elucidate complex

29

aerosol-climate interactions.

Increasing aerosol number concentration of aerosol particles are found to be

associated with decreasing droplet sizes for both convective (Sporre et al., 2014a)

and low-level clouds (Sporre et al., 2014b). The cloud optical thickness is however

not found to be affected by the aerosol number concentrations for either cloud

type. This implies that no first indirect aerosol effect can be detected in these

clouds. The precipitation intensity is nevertheless found to decrease in air-masses

with higher aerosol number concentrations for both the convective and low-level

clouds and hence the second indirect aerosol effect is detected in these datasets.

The meteorological conditions are found to affect the clouds but not the aerosol-

cloud relationships.

S4.O2 (9:45-10:00) Biogenic SOA formation in the subarctic – Comparison between process models of varying complexity E. Hermansson, P. Roldin, A. Rusanen, D. Mogensen, N. Kivekäs, M. Boy and E. Swietlicki (A. Kristensson)

Biogenic volatile organic compounds (BVOCs) emitted by the vegetation play an

important role for the aerosol mass loadings since the oxidation products of these

compounds can take part in the formation and growth of secondary organic

aerosols (SOA). The concentrations and properties of BVOCs and their oxidation

products are poorly characterized, which lead to high uncertainties in modeled

SOA mass and properties.

The aim of this study is to investigate the effect that different gas phase oxidation

schemes have on the modeled evolution of SOA at atmospheric conditions. SOA

formation is modeled along an air mass trajectory over the northern European

boreal forest, passing three measurement sites: Abisko, Pallas and Värriö, using

two aerosol dynamics box models. Both models are coupled to the near-explicit

Master Chemical Mechanism version 3.2 (MCMv3.2) which is used when

predicting the oxidation products of the BVOCs. This near-explicit treatment of

organic gas-phase oxidation was compared to different oxidation schemes that

use the volatility basis set (VBS) approach, in order to get an indication of the

uncertainties and importance of different processes in the VBS regarding SOA

formation.

The result of the study shows that the modeled mass concentration of SOA is

highly dependent on the organic oxidation scheme used to predict the oxidation

products. The resulting SOA mass modeled with different VBS-schemes varies by a

factor of about 7 depending on how the first generation oxidation products are

parameterized and how they subsequently age. Since the VBS approach is

frequently used in regional and global climate models due to its relatively simple

treatment of the oxidation products compared to near-explicit oxidation schemes,

a better

understanding of the abovementioned processes are needed. The use of box

model simulations can indicate which processes that need to be further studied in

order to parameterize them better.

S4.O3 (10:00-10:15) Consistency of aerosol trends using ACTRIS data together with AeroCom, EMEP and MACC model data

Michael Schulz, Jan Griesfeller, Hilde Fagerli, Svetlana Tsyro, Paul Eckhardt,

Cathrine Lund Myhre, Markus Fiebig, Wenche Aas

Aerosol trends in Europe after 1990 show a significant shift in composition due to

30

the reduction in sulphate content. Nitrate should have been reduced as well

according to emission inventories. Such shift in composition should be reflected in

several aerosol parameters, from optical properties to aerosol size and

composition. We investigate here with the help of consistent model simulations

from AeroCom, EMEP and MACC how consistent such trends are with observed

data, including those from ACTRIS. The work makes extensive use of the

EBAS/ACTRIS data center and a new feature of the AeroCom web interface

showing specific ACTRIS related model/data comparisons.

S4.O4 (10:15-10:30) Organic aerosol global model evaluation, process understanding and source attribution based on ACTRIS/EUSAAR observations Maria Kanakidou et al. (N. Mihalopoulos)

The use of EUSAAR/ACTRIS OC data for the OA AEROCOM intercomparison

exercise (Tsigaridis et al ACPD, 2014) and our plans to further use ACTRIS data for

model evaluation and source understanding. This includes the current status of

global modeling of the organic aerosol (OA) in the troposphere and analyze the

differences between models as well as between models and observations.

10:30-11:00 Coffee break

Oral session S1b: Scientific achievements at ACTRIS stations

Thursday, 12 June, 11:00 – 12:00

Chairs: Paolo Laj, Michael Schulz S1.O9 (11:00-11:15) Mineral dust aerosols from the Sahara desert over Moussala in the period 2011

and 2013

Assen Tchorbadjieff, Ivo Kalapov

The Basic Environmental Observatory (BEO) at Moussala is the only operational

high mountain observatory for real time monitoring of high altitude aerosols in

South-East Europe. It is separated from Sahara desert only by Mediterranean and

it is very common to be on the way of air masses transport from the desert,

usually in spring and early summer. The frequency and intensity of air masses

with Sahara origin are random with different impact on clouds, atmospheric

dynamics and chemistry, air quality, and biogeochemical cycles in the region.

They are mainly with rare concentrations of minerals. However, it was observed a

number of very strong events not only in the region of Moussala, but in the

nearby territory. This paper summarizes recent progress on monitoring and

analysing the dust detection from the Sahara based on measurements performed

on Moussala. The data is compared with a relative satellite sources and available

LIDAR observation in Sofia, the city located in about 50 km away from Moussala.

S1.O10 (11:15-11:30) C2H6, NO2 and HCHO measurements at the high-altitude alpine station of Jungfraujoch (46.5°N, 8.0°E) B. Dils, F. Hendrick, J. Cui, B. Franco, D. Helmig, S. Henne, C. Hoerger, J. Hueber, E. Mahieu, J.-F. Müller, S. Reimann, T. Seitz, M. Steinbacher, T. Stavrakou, R. Sussmann, M. Van Roozendael, and M. De Mazière

In this presentation, we investigate the capability of retrieving NO2 and HCHO

near-surface concentrations and tropospheric vertical column densities from

MAX-DOAS measurements at the high-altitude station of Jungfraujoch (3580m

asl) in the Swiss Alps. In the case of HCHO, our retrievals are compared to

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collocated FTIR observations, taking into account the difference in vertical

resolution between both techniques. Simulations from the 3D-CTM IMAGES are

also used to further assess the observed seasonal and diurnal cycles of HCHO

surface concentration and vertical column. Regarding NO2, retrieved near-surface

concentrations are compared to in-situ observations simultaneously performed at

the station. The difference in spatial representativeness between both data sets is

taken into account using the FLEXPART trajectory model. We also compared C2H6

in-situ with FTIR total column measurements at the Jungfraujoch station. We

were particularly interested in to what extent in situ data contains information

about the atmosphere above the station. To explore this we corrected IMAGES

model profiles with the in situ data, using various degrees of vertical impact, prior

to its comparison with FTIR data.

S1.O11 (11:30-11:45) Sources, seasonal variability and oxidation state of organic aerosol in the Eastern Mediterranean A. Bougiatioti, I. Stavroulas, E. Kostenidou, F. Canonaco, A.S.H. Prévôt, S.N. Pandis and N. Mihalopoulos

The sources, seasonal variability and oxidation state of organic aerosol were

studied at the remote background site of Finokalia, Crete (Eastern

Mediterranean) for a period of 16 months (June 2012 to December 2013). The

study is based on measurements performed using an Aerosol Chemical Speciation

Monitor (ACSM) and the resulting organic components identified by Positive

Matrix Factorization (PMF) analysis of the organic mass spectra. Different factors

and subsequently different sources are identified depending on the season, each

factor having varying contribution to the total organic aerosol (OA). Overall the

O/C ratio of the total OA varies between 0.61 and 1.31, with a mean value of

1.06±0.13, which is within the observed values of low-volatility oxygenated

organic aerosol (OOA) and dicarboxylic acids. This ratio can be a proxy for the

oxidation state and its variability can reflect the variations in OA age during the

measurement period. Based on PMF analysis, throughout the study period the

factor that exhibits the largest contribution is a highly oxygenated OA with

pronounced relative intensity of m/z 18 and 44, which is furthermore supported

by its elevated O/C (1.25±0.07). It exhibits a seasonal cycle with minimum

average concentrations during winter (1.07±0.82 μg m-3) and maximum during

summer (2.13±1.07 μg m-3) and respective contribution of 52% and 58%. Long-

range transport of biomass burning from Southeastern Europe and countries

surrounding the Black Sea influence the site during two periods (April-May and

July-September). The fresh BBOA factor during these periods is estimated to

contribute on average 17.1±2.2% to the total OA. A distinct regional source of

olive tree branches burning, which is a common agricultural waste management

practice in the Mediterranean area after the annual pruning of olive trees, is also

identified from November to February (not included in the aforementioned

BBOA). The main difference between the mass spectrum of the olive tree

branches burning and other published biomass burning spectra is the almost

equal intensities of m/z 43 and 44 and the lower intensity of m/z 60. The olive

tree burning factor can contribute up to 48% of the identified OA during

wintertime. This source can be regarded as an important emission source during

this season in Mediterranean area, as the olive tree branches burning mainly

takes place when there is no rainfall or high wind speeds, which could scavenge

the produced particulate matter.

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S1.O12 (11:45-12:00) Vertical profiles of fine-mode and coarse-mode aerosol concentrations derived from combined lidar and sunphotometer observations Ulla Wandinger, Anatoli Chaikovsky, Oleg Dubovik, Anton Lopatin, Albert Ansmann, et al.

The ACTRIS Joint Research Activity “Lidar and sunphotometer — Improved

instruments, integrated observations and combined algorithms” aims at the

development and implementation of integrated lidar and sunphotometer

inversion algorithms to obtain advanced information on aerosol microphysical

properties. Two different algorithms have been developed and tested. The first

one is the Lidar/Radiometer Inversion Code (LIRIC) created at the Institute of

Physics of the National Academy of Sciences of Belarus, Minsk. The second

algorithm is the Generalized Aerosol Retrieval from Radiometer and Lidar

Combined data (GARRLiC) developed at Laboratoire d’Optique Atmosphérique,

Lille. The concepts of these two algorithms are slightly different. Whereas LIRIC

makes use of final sunphotometer products of columnar aerosol microphysical

properties and multiwavelength lidar signals, GARRLiC starts with sun and sky

radiances measured with radiometer and performs a complete new inversion of

both radiometer and lidar data.

Both algorithms have been applied to combined EARLINET and AERONET

observations at selected stations distributed over Europe to retrieve volume and

mass concentration profiles for fine-mode and coarse-mode particles. If the

particle linear depolarization ratio is measured with lidar, also the contributions

of non-spherical and spherical scatterers can be distinguished. Thus the retrievals

allow, e.g., the separation of dust from natural source (coarse, non-spherical

particles) and anthropogenic pollution or smoke (fine particles).

The potential and limitations of the methods will be discussed based on selected

measurement cases from ACTRIS stations in the Mediterranean, Central and

Eastern Europe. Comparisons with lidar stand-alone retrievals and with in situ

observations will be presented, and an outlook for further implementation of the

algorithms in the network will be given.

Poster session P3 / P4: ACTRIS, Model and Satellite / Scientific achievements at ACTRIS

stations

Thursday, 12 June, 12:00 – 13:00 and 16:00 – 19:00

P3.1 Analysis of dust transport over Barcelona using lidar and DREAM model: some

unusual case studies

Smadar Egert, Pavel Kishcha, Michaël Sicard, Adolfo Comerón, Pinhas Alpert

The Geophysics group of Tel Aviv University (TAU) is a part of an international

project with the KIT (Karlsruhe Institute of Technology, KIT/Germany) called DEad

SEa Research Venue (DESERVE). The goal of one part of this project is to monitor

the meteorological and aerosol properties in a 10X10 km cube over the Dead Sea.

Remote atmospheric measurements and COSMO (Consortium for Small-scale

Modeling) model are the planned tools for evaluation. The TAU group performs

regularly DREAM-8 (Dust Regional Atmospheric Model) calculations of dust

transport, whose predictions are a tool to calibrate the COSMO model, which has

33

never been used over Israel. At ground level, this calibration will be performed at

high resolution using the Israeli network of PM particle measurements. In order to

calibrate the vertical profiles, DREAM-8 outputs are compared to the Universitat

Politècnica de Catalunya (UPC) lidar observations during two dust outbreaks in

Barcelona in the period 6 – 16 June 2014. Hysplit backtrajectories and sun-

photometer measurements were used to confirm the aerosol origin.

The DREAM model predicts the layer height and dust mass concentration. The

lidar-derived mass concentration profiles are calculated by dividing the measured

extinction profiles by a constant specific extinction cross section taken from

previous works at the UPC and published in the literature. It is found that in terms

of structure, DREAM-8 predictions agree quite well with the dust layer height and

thickness observed by the lidar. In terms of mass concentration, DREAM-8 always

overestimates by a factor 2 to 10 the concentration retrieved from the lidar

observations. A pattern is observed in the outcome of the comparisons between

the model and the observations: the highest the concentration difference, the

best the vertical structure agrees. In spite of the dream predictions of the dust

layer, the Hysplit predicts Saharan dust only in part of the cases. The analysis will

be presented as an interesting case and a basis for discussion for the origin of the

discrepancies found.

P3.2 Aerosol typing over Europe from ground-based lidar measurements and its

benefits for spaceborne lidar observations

Anja Schwarz, Ulla Wandinger, Ina Mattis, and the EARLINET consortium

This study shows how advanced ground-based lidar measurements of EARLINET

are used to validate lidar observations of CALIOP (Cloud-Aerosol Lidar with

Orthogonal Polarization) onboard the polar-orbiting satellite CALIPSO (Cloud-

Aerosol Lidar and Infrared Pathfinder Satellite Observations).

CALIOP is operating at 532 and 1064 nm and provides vertically resolved

information on aerosol and cloud parameters on a global scale since June 2006.

For the analysis of data obtained from this elastic-backscatter lidar, a priori

assumptions on a fixed aerosol-type-dependent lidar ratio (extinction-to-

backscatter ratio) are required in order to derive the particle extinction coefficient

and thus the aerosol optical thickness. In contrast, advanced ground-based lidars

provide the aerosol backscatter and extinction coefficients independently and at

multiple wavelengths as a function of aerosol type.

For the present study, EARLINET data obtained during the ESA-CALIPSO project

(EARLINET’s Spaceborne-related Activity during the CALIPSO mission), funded by

the European Space Agency, are used. These ground-based observations were

performed in correlation to CALIPSO overpasses based on a sophisticated

measurement schedule. Aerosol optical properties were evaluated in detail and

compared to the output of the automated CALIPSO data retrieval algorithms

based on a critical assessment of the implemented aerosol classification scheme.

Results of the comparisons are shown.

The performed study is also a valuable basis for future lidar measurements from

space. The ADM–Aeolus and EarthCARE missions will continue and extend

spaceborne lidar observations. For these missions 355-nm high-spectral-

resolution lidars will be applied. To relate data from the different sensors and to

harmonize continuous global observations of aerosol properties from space a

statistical evaluation of aerosol optical properties obtained from EARLINET

34

measurements was carried out to determine wavelength conversion factors.

Results are presented for pure aerosol types and frequently observed aerosol

mixtures.

P3.3 Long-term aerosol study on continental scale through ACTRIS/EARLINET vertical

profiles

Lucia Mona, and EARLINET team

EARLINET (European Aerosol Research Lidar Network) has been providing aerosol

optical properties vertical profiles over Europe since May 2000. All EARLINET

stations perform almost simultaneously measurements three times per week

following a scheduling established in 2000. Besides these climatological

measurements, additional measurements are performed in order to monitor

special events (as volcanic eruptions and desert dust intrusion), for satellite data

evaluation and integrated studies and during intensive measurements

campaigns. Aerosol optical properties vertical profiles are freely available at

www.earlinet.org and through ACRIS data center http://www.actris.net/. This

data are currently published on the CERA database with an associated doi

number.

Long-term aerosol observations performed within EARLINET allows a

climatological study of aerosol properties over Europe. In particular, EARLINET

Raman stations provide direct measurement of extinction profiles, and therefore

of the aerosol optical depth (AOD), a key parameter for understanding the

aerosol role on radiation budget. The free troposphere contribution to AOD and

altitude of lofted layers are provided thanks to the vertical profiling capability of

lidar technique. The representativeness of EARLINET regular scheduling for

climatological studies is investigating through the comparison with AERONET and

MODIS measurements. We find that the regular measurements schedule is

sufficient for climatological studies. In addition lidar punctual measurements are

representative for a larger area (1°x1°) in a climatological sense. Long term

analysis of EARLINET profiles shows that the AOD in generally decreasing over

Europe in agreement with both passive-sensors and in situ measurements.

Moreover, a reduction of the contribution to the total AOD of the lowest altitude

range is found in particular for the Central Mediterranean region. The analysis of

lidar ratio and Angstrom exponent values Indicates a slight modifications towards

less polluted and bigger particles in the PBL over Europe.

P3.4 Aerosol Extinction Profiles With The Emep Model: First Evaluation Through

Earlinet Profiles

S. Tsyro,M. Schulz, L. Mona, N. Papagiannopoulos, W. Aas

One of the main applications of the EMEP/MSC-W model is to provide - for policy

related assessments - the calculations of current levels and future scenarios of

PM10 and PM2.5. Accurate calculation of mineral dust is important to reproduce

PM levels and episodes, including exceedances of critical values. Good estimates

of mineral dust deposition are necessary forassessment of ecosystems recovery

from acidification due to base cautions.On the global scale, accurate modeling of

desert dust is essential for making robust estimates of aerosol loads, solar

radiation extinction and aerosol radiative effects.

EARLINET aerosol extinction profiles measured during the ACTRIS Summer 2012

Campaign are compared to EMEP model for evaluating model performance in

35

terms of dust contribution and of aerosol extinction.

The model runs are performed on both regional and global scales. Modeling of

windblown dust is associated with large uncertainties, therefore a series of tests

is performed to study the sensitivity of results to uncertain parameterization and

input parameters.Furthermore, as windblown dust generation is rather a sub-grid

process, the effect of model’s resolution on calculated dust concentrations is

considered.

We make combined use of observed and modeled dust data to look closer at dust

events. In addition to situ PM measurements, EARLINET aerosol extinction profiles

have facilitated identifying such events. Understanding air pollution episodes in

Southern Europe requires taking into account Saharan dust intrusions. Making

use of EMEP global calculations, we show the advantage of using in the regional

scale EMEP model time resolved, consistent boundary conditions as opposed to

climatological dust fields.

P4.1 Real-time detection of Bioaerosols by Mass Spectrometry and Fluorescence

methods during the BIODETECT 2014 campaign at CEA/LSCE/ACTRIS SUPERSITE

(Saclay, France)

R. Sarda-Estève, J. Sciare, N.Bonnaire, C. Junot, F. Fennaille, F. Bercher, M.

Thibaudon, B.Baisnee, M. Gallagher, A. Gabey, V. E. Foot, J. A. Huffman, U.

Pöschl, H.Su, D. Kiselev, S.Sampo, O. Favez, J. Jayne,P. Croteau, A. Prevot, A.

Vlachou, I.El. Haddad, J-M. Roux, M. H. Nadal, C. Bossuet and L. Olmedo

The French Atomic Energy Commission (CEA) has developed a new on line mass

spectrometry method to detect atmospheric fungal spores (Sarda Esteve et al.,

AAAR 2013) under the Bio Chemical Collectors (BCC) research project. This

method has been compared with a traditional method from the National Network

of Survey for Airborne contaminants (RNSA) to identify Cladosporium events and

has shown good agreement with microscopy techniques. Real-time

measurements of bio-aerosols using light-induced fluorescence (LIF) techniques

have also been performed widely, both for bio-aerosol quantification and to

support ice nucleation studies (e.g. Despres et al., 2012). Recent work has sought

to better understand the variability in observed fluorescence recorded using LIF

instruments (Huffman et al., 2013, O’Connor et al., 2014). Novel data analysis

methods are also required to effectively interpret the datasets produced by such

instruments, which can exhibit high dimensionality. Robinson et al., (2013)

successfully distinguished between calibration particles measured using a WIBS

4A by applying a clustering algorithm to the data. They went on to apply this

algorithm to ambient datasets and attributed particular clusters to bacteria and

fungal spores (Crawford et al., 2014).

To understand the major processes affecting fluorescent aerosol particles, it is

necessary to intercompare these real-time methods with measurements of

biological targets that provide more detailed chemical information, such as real-

time mass spectrometry. An intensive measurement campaign, BIODETECT 2014,

will take place at the LSCE-SIRTA ACTRIS supersite outside Paris in summer

between the 7th of July and the 8th of August. This study may help identify

potential new technologies for monitoring the spread of airborne pathogens and

other bio-aerosols. During this period of the year, bacteria and fungal spore are

expected to be emitted to the air in high concentration. These bio-aerosol events

36

can be used as proxies for airborne pathogens spreading through an

urban/suburban influenced environment.

P4.2 Direct, longwave radiative forcing of mineral dust: sensitivity study and

improvement of its estimation by means of tools recently developed by the

EARLINET community

Michaël Sicard, Constantino Muñoz, Adolfo Comerón, Alejandro Rodríguez

Atmospheric aerosols have a remarkable effect on the Earth‐atmosphere

radiative budget. Indeed, aerosols and their interactions with clouds contribute to

the largest uncertainties in the estimation of the Earth’s changing energy budget.

Nowadays many radiative transfer models have been developed to locally

estimate the aerosol direct radiative forcing (RF). In the longwave (LW) spectral

range, the aerosol radiative properties are usually estimated theoretically with a

Mie code. The parameter that contains the absorption and scattering quantities,

the extinction coefficient, is normalized to the extinction coefficient in the

shortwave spectral range, most of the time in the visible spectral range, or to the

number concentration. As measurements of the extinction coefficient or of its

integral, the optical thickness, are available in the shortwave spectral range, the

equivalent extinction coefficient or optical thickness in the LW spectral range

can be deduced thanks to that normalized, theoretical extinction coefficient.

The first objective of this research is to perform a sensitivity study of mineral dust

direct radiative forcing as a function of their properties. The radiative transfer

model GAME, which can compute vertically resolved shortwave and longwave

values of aerosol radiative forcing, is used. Before developing the sensitivity

analysis, the aerosol radiative transfer model is validated by comparing

its outputs with results published previously. Radiative forcing simulations in the

longwave show an important sensitivity to the following parameters: aerosol size

and refractive index, aerosol vertical distribution, humidity, surface temperature

and albedo. The second objective of this work is to investigate how the knowledge

of the vertically‐resolved fine and coarse mode aerosol optical thickness modifies

the LW RF. Since relatively little the EARLINET community has developed codes

that combine sun‐photometer and lidar data to retrieve a set of parameters

vertically‐resolved related to the size distribution (fine and coarse mode extinction

coefficients, fine and coarse mode volumetric concentrations, etc.). We

concentrate on the case of mineral dust whose size distribution is often

dominated by the coarse mode. This work demonstrates that the knowledge of

the vertically‐resolved fine and coarse mode aerosol optical thickness modifies

the LW RF as compared to the classical approach with a total aerosol optical

thickness. The results show that when the coarse mode predominates the

classical approach underestimates the dust LW RF by 4 to 20 %.

P4.3 OC and EC analyzed in PM using thermo-graphic or thermo-optical method at

Melpitz site in Germany– a comparison for 2012-13

Gerald Spindler, Anke Rödger, Laurent Poulain, Konrad Müller, Hartmut

Herrmann

Since 2002 organic carbon (OC) and elemental carbon (EC), in sum total carbon

(TC), were quantified at TROPOS with a carbon analyzer, (C/Smax) using the VDI-

Method (TGVDI), for quartz filter high-volume-samples (HV).

In 2012 the thermo-optical method (TO) be introduced (Sunset Laboratory Inc.) to

provide comparable results for the daily PM10, PM2.5 and PM1 samples from

37

Melpitz site for international networks (ACTRIS, EMEP). The most common

temperature protocol in Europe EUSAAR2 with transmission detection was used

(TOTEUSAAR2).

To avoid parallel analysis we derive empirical factors (F) to recalculate OC, EC and

TC from 21 month (start January 2012) from TG and TO analysis (equation 1)

[OC;EC;TC]TGVDI = F x [OC;EC;TC]TOTEUSAAR2 (1)

TGVDI deliver TC results which are in the mean about 85% lower than for

TOTEUSAAR2. The reason is the lower temperature (650°C) in comparison to the

final temperature of the EUSAAR2-protocoll (850°C). The TGVDI without charring

correction provides in the mean lower OC values (F=0.72) and higher EC values

(F=1.58) in comparison to TOTEUSAAR2. All derived F show very low variability’s

for the particle sizes (PM10, PM2.5, PM1). Factors F are 0.68 (0.76) for OC, 1.42

(1.68) for EC, and 0.85 (0.85) for TC, respectively, for days with air-mass type

marine compared to continental (in brackets). A comparison between summer

and winter (in brackets) results in F of 0.64 (0.76) for OC, 2.23 (1.44) for EC and

0.83 (0.86) for TC. In summary, for the whole time the factor F show a minor

variability and allows re-calculation of long-time means for OC, EC and TC.

For means over season or over days with different air masses a re-calculation only

for TC can recommended, the split between OC and EC may vary.

A comparison for PM1 OC between TOTEUSAAR2 and AMS-measurements gives

indication for a more realistic chemically originated result.

P4.4 BASTA – FMCW Cloud radar at SIRTA

Julien Delanoë, Jean‐Paul Vinson, Williams Brett, Christophe Caudoux, Fabrice

Bertrand, Ruben Hallali, Jacques Parent du Chatelet, Alain Protat, Martial

Haeffelin, Jean‐Charles Dupont

France LATMOS (CNRS/UVSQ/UPMC) laboratory has extensive experience in the

meteorological field and especially in cloud observation using Doppler radar. We

have recently developed a new cloud Doppler radar at 95GHz, called BASTA. The

BASTA Doppler radar is a frequency modulated continuous wave (FMCW) radar

and it does not require high transmitting power unlike very expensive pulsed

radar. This technical option takes advantage of the latest developments in signal

processing techniques and allows one to drastically reduce the price of the

emitter. Our in house prototype provides real time 24/7 vertical observations and

has been operated for several years without any significant failure at SIRTA

(Palaiseau, France). This radar is ideal for cloud and fog studies. Four

simultaneous resolutions are available: for instance a 12.5m resolution is

dedicated to low clouds and fog, a 25m resolution is dedicated to midlevel clouds

and, 100m and 200m resolutions are especially designed for high altitude ice

clouds such as cirrus up to 12 km. Therefore this radar opens a way to cloud radar

networking due to its relative low coast and its simplicity to operate. It is also

envisioned to deploy such a radar on airports to monitor fog and contribute to

improve security. Due to its technical characteristics this radar can be easily

calibrated using a target mounted on a mast. This advantage coupled to its high

mobile capability could make it a mobile calibrator for radars that are more

challenging to calibrate. We will present our latest version of the prototype and a

few results. Session 1: Scientific achievements at ACTRIS stations.

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P4.5 Analysis of Highly Time- and Size-Resolved Particle Number Size Distribution

Data at Košetice station

Naděžda Zíková, Jakub Ondráček, Jaroslav Schwarz, Jiří Smolík, Vladimír Ždímal

Five years of continuous SMPS data measured at the rural background station

Košetice observatory is presented, and the first two years of data are statistically

analyzed. The evaluation was performed on time scales from years to days, and

an overall new particle formation (NPF) frequency analysis was done as well. The

annual average total concentration was found to be 6.6 x 103 #/ccm, the particle

size distribution has a well expressed accumulation mode and high variability in

particles sizes below 50 nm. In the seasonal data, particles of the smallest sizes

(smaller than 50 nm) were of high concentrations in summer, on the contrary, of

the lowest concentrations in winter. Particles of the biggest sizes (over 300 nm)

showed the opposite behaviour. The analysis of NPF events revealed a strong

annual cycle peaking in spring and summer and dropping in winter. In monthly

data, the global minimal of total concentrations was recorded in December, the

global maximum in June. Weekly cycle analysis proved that the station is suitably

characterised as a rural background – the weekly cycle was statistically

insignificant on most days. The typical daily cycle of total concentrations showed

its minimum between 3 and 6 AM, its maximum at about 6 PM. Particles under

50 nm in diameter, compared to particles larger than 50 nm, exhibited higher

daily amplitude.

P4.6 Combining vertical-wind statistics and Cloudnet microphysical products in mid-

level clouds

Johannes Bühl, Patric Seifert, Ronny Engelmann, and Albert Ansmann

Mixed-phase altocumulus or altostratus clouds should glaciate within minutes,

due to the Wegener-Bergeron-Findeisen process. Observations of mixed-phase

mid-level clouds (2-8 km height) contradict this expectation. They were found to

be stable over hours in ground-based experiments at our field sites and in aircraft

measurements. The main reason for that are permanently occurring up- and

downdrafts. To observe such complex scenarios from the ground, combined lidar

and radar measurements are essential.

We probe mid-level mixed-phase clouds (altocumulus, altostratus) with a

vertically pointing Doppler lidar, a depolarization lidar, a microwave radiometer

and a 35-GHz cloud radar to investigate the impact of atmospheric upward and

downward motion on the physical phase composition of these clouds. The vertical

velocities at cloud base (Doppler lidar) and the microphysical properties of the

clouds (Cloudnet retrievals from combined radar, microwave and lidar

observations) are obtained simultaneously. We identify virga particles below the

clouds and discriminate ice particles and droplets by means of the depolarization

lidar and radar techniques.

Comprehensive statistics of cloud phases and their associated vertical velocities

are established from Cloudnet microphysical products combined with Doppler

lidar measurements. Case studies from the SAMUM-2 campaign at Cape Verde

(2008) and from the UDINE campaign (Up- and Downdrafts and Drop and Ice

Nucleation Experiment) at Leipzig (2010-2013) are presented to compare cloud

properties in tropical and mid-latitude environments.

39

P4.7 Investigation of aerosol-cloud interactions with dual-field-of-view Raman lidar

measurements

Jörg Schmidt, Johannes Bühl, Albert Ansmann, and Ulla Wandinger

This study investigates aerosol-cloud interactions over Leipzig, Germany, by

means of the dual-field-of-view (dual-FOV) Raman lidar technique. Thereby, it

serves the ACTRIS WP22 “A framework for cloud-aerosol interaction studies”.

Dual-FOV Raman lidar probings of water clouds are performed with two FOVs. In

this way, profiles of the cloud extinction coefficient, cloud droplet effective radius,

liquid water content (LWC), and cloud droplet number concentration (CDNC) are

obtained up to a penetration depth of about 150 m.

Twenty-nine dual-FOV Raman lidar measurements are considered for a statistical

analysis of aerosol-cloud interactions. The correlation between the aerosol

particle extinction coefficient a below the cloud and the CDNC N at cloud base is

investigated by means of ACIN values (ACIN =

- d ln N / d ln a). For the aerosol layer which stretches from 300 to 1000 m below

cloud base height and the CDNC obtained 30 to 70 m above cloud base ACIN =

0.32 +/- 0.19 is obtained.

Through the cloud-profiling capability of the dual-FOV Raman lidar technique, the

dependence of ACIN on the cloud penetration depth is investigated. A strong

decrease of aerosol-cloud correlation to ACIN = 0.00 +/- 0.31 is observed for a

higher cloud penetration depth of 70 to 120 m. This finding corroborates that

aerosol-cloud interactions are most pronounced at cloud base where the aerosol

particles are mixed into the cloud and other cloud processes are less dominant.

Furthermore, the effect of the vertical wind speed on aerosol-cloud interactions is

investigated with combined measurements of the dual-FOV Raman lidar and a

Doppler wind lidar. Significantly higher ACIN values are obtained for cloud

updraft regions with ACIN = 0.77 +/- 0.36 and ACIN = 0.41 +/- 0.39 for cloud

penetration depths of 30 to 70 m and 70 to 120 m, respectively.

This study investigates aerosol-cloud interactions over Leipzig, Germany, by

means of the dual-field-of-view (dual-FOV) Raman lidar technique. Thereby, it

serves the ACTRIS WP22 “A framework for cloud-aerosol interaction studies”.

Dual-FOV Raman lidar probings of water clouds are performed with two FOVs. In

this way, profiles of the cloud extinction coefficient, cloud droplet effective radius,

liquid water content (LWC), and cloud droplet number concentration (CDNC) are

obtained up to a penetration depth of about 150 m.

Twenty-nine dual-FOV Raman lidar measurements are considered for a statistical

analysis of aerosol-cloud interactions. The correlation between the aerosol

particle extinction coefficient a below the cloud and the CDNC N at cloud base is

investigated by means of ACIN values (ACIN =

- d ln N / d ln a). For the aerosol layer which stretches from 300 to 1000 m below

cloud base height and the CDNC obtained 30 to 70 m above cloud base ACIN =

0.32 +/- 0.19 is obtained.

Through the cloud-profiling capability of the dual-FOV Raman lidar technique, the

40

dependence of ACIN on the cloud penetration depth is investigated. A strong

decrease of aerosol-cloud correlation to ACIN = 0.00 +/- 0.31 is observed for a

higher cloud penetration depth of 70 to 120 m. This finding corroborates that

aerosol-cloud interactions are most pronounced at cloud base where the aerosol

particles are mixed into the cloud and other cloud processes are less dominant.

Furthermore, the effect of the vertical wind speed on aerosol-cloud interactions is

investigated with combined measurements of the dual-FOV Raman lidar and a

Doppler wind lidar. Significantly higher ACIN values are obtained for cloud

updraft regions with ACIN = 0.77 +/- 0.36 and ACIN = 0.41 +/- 0.39 for cloud

penetration depths of 30 to 70 m and 70 to 120 m, respectively.

P4.8 The relationship between aerosol properties, temperature, and the efficiency

of heterogeneous ice formation as observed with lidar

Patric Seifert, Thomas Kanitz, and Albert Ansmann

The vertical distribution of ice and super-cooled liquid water fundamentally

controls the radiation budget of the atmosphere and the type and intensity of

precipitation. Long-term lidar observations performed within EARLINET by

TROPOS, Leipzig, Germany were used to investigate the relationship between

temperature and the probability of heterogeneous ice formation in super-cooled

clouds for atmospheric temperatures between 0 and -40 °C. These studies dealt

with three main questions: How does (1) Saharan dust and (2) volcanic ash affect

the efficiency of heterogeneous ice nucleation as a function of cloud-top

temperature and (3) how efficient does heterogeneous ice formation occur in the

rather aerosol-burden atmosphere above Central Europe compared to other

regions of the Earth?

Information about the temporal and vertical extent of the observed cloud layers

were obtained from the received range-corrected signal. The phase state (either

pure liquid or ice-containing) was derived from the volume linear depolarization

ratio measured with lidar.

The analysis of ten years of lidar measurements at TROPOS revealed that clouds

contain ice 50% more frequently at cloud-top temperatures between -15 and -10

°C under dust-laden conditions compared to dust-free conditions (75% instead of

50%). Similar results as for dust-laden conditions were obtained for clouds

embedded in volcanic ash after the eruption of the Eyjafjallajökull volcano in April

2010. From the comparison of the long-term Leipzig dataset to respective

datasets from Punta Arenas, Chile and Praia, Cape Verde it was found that

heterogeneous ice formation is in general more efficient over Central Europe. At

the tropical and southern-hemispheric sites of Praia and Punta Arenas,

respectively, significant ice formation was only observed at temperatures below -

20 °C. This finding implies that the rather high background aerosol load in the

northern midlatitudes has a strong impact on the efficiency of heterogeneous ice

formation.

P4.9 Joint analysis of continental and regional background environments in the

Western Mediterranean: PM1 and PM10 concentrations and composition

A. Ripoll, M. C. Minguillón, J. Pey, N. Pérez, X. Querol, A. Alastuey

Atmospheric aerosol concentrations and composition were simultaneously

41

studied at a continental (Montsec, MSC, 1570 m a.s.l.) and a regional (Montseny,

MSY, 720 m a.s.l) background site in the Western Mediterranean Basin (WMB) for

a 3 year period.

Time variation of aerosol concentrations and composition was investigated as a

function of the origin of air masses. The diverse meteorological episodes showed

different influence at regional and continental scale. When long-range transport

from Central and Eastern Europe and from North Africa occurs, the continental

background site is frequently more influenced, thus indicating a preferential

transport at high altitude layers. Conversely, the regional background was more

influenced by regional processes. In winter, anticyclonic conditions enhance the

stagnation of air masses with the consequent accumulation of pollutants at

regional scale in the WMB, whereas the continental background site remains in

the free troposphere. Totally different conditions drive the aerosol

phenomenology in summer. Weak pressure gradients and elevated insolation

generate recirculation of air masses and enhances the development of the PBL,

causing the aging of aerosols and incrementing pollutant concentrations over a

larger area, including the continental background. This is reflected in a more

similar relative composition and absolute concentrations of PM components at

both regional and continental background environments in the warmer season

Our results highlight the importance of the NPF processes in southern Europe,

reveal a relatively lower contribution of anthropogenic pollutants (mainly

biomass combustion) with respect to central Europe, and underline the

contribution of natural long-range transport such as Saharan dust.

P4.10 Results of the ACTRIS NA 4 VOC Round Robin Intercomparison Experiment for

Monoterpenes

Anja Werner, C. C. Hoerger, C. Plass-Duelmer, S. Reimann, R. Steinbrecher, E.

Eckart, N. Bonnaire, A. Colomb, R. Connolly, J. Diskova, P. Dummitrean, C. Ehlers,

V. Gros, H. Hakola, M. Hill, J. R.Hopkins, J. Jaeger, M. Leuchner, K. Michl, E.

Nemitz, S. Sauvage

Biogenic volatile organic compounds (BVOC) play an important role in summer-

time tropospheric chemistry and in secondary organic aerosol formation. They are

produced by vegetation under daylight conditions and are mainly depleted by

reaction with OH and O3, yielding atmospheric lifetimes of minutes to hours. The

amount in the atmosphere thus varies between less than 1ppt to few ppb and the

rather reactive compounds are challenging to quantify. State of the art

instrumentation for BVOC is usually gas chromatography with either flame

ionization detection (GC-FID) or with mass spectrometry (GC-MS). The Proton

Transfer mass spectrometry (PTR-MS) is able to measure monoterpenes in an air

stream directly, but cannot specify between individual BVOCs. However, GC-

systems have the ability to quantitate individual compounds, but they require a

complex multi-step sample preparation process which represents a large

potential for errors. Further challenge is a proper calibration, which is usually

performed with pressurized whole air or synthetic mixtures stored in cylinders or

by liquid injection.

In order to evaluate the performance of the available instruments within ACTRIS

VOC network, a Round-Robin-intercomparison for VOC was performed in NA4

(Trace gases networking: Volatile organic carbon and nitrogen oxides). Two sets

of test gases comprising each a cylinder with a whole air sample and a cylinder

with a synthetic 30-component VOC in N2 mixture were circled among twenty

42

stations all over Europe. Results of this intercomparison for alkanes, alkenes,

alkynes and aromatics are shown in an accompanying presentation by C. C.

Hoerger et al.. The synthetic VOC mixture included nine monoterpenes and also

three trimethylbenzenes. These were measured by a subset of the participating

stations applying different GC-FID and GC-MS techniques and results will be

shown here.

P4.11 Study of droplet activation in thin clouds using ground-based lidar, Doppler

radar and microwave techniques

M. Rosoldi, P. Gumà Claramunt, F. Madonna, F. Amato, A. Amodeo, G. D’Amico,

A. Giunta, L. Mona, N. Papagiannopoulos and G. Pappalardo

Clouds change their macrophysical, microphysical and optical properties as a

result of their interaction with aerosols. These processes are still not accurately

quantified and parameterized in weather and climate numerical models and

accurate estimations of aerosol and cloud properties, using surface-based

measurements , are needed to improve their modeling.

Thin liquid water clouds represent an interesting target to infer quantitative

information on droplet activation process, because ground-based active remote

sensing techniques, such as Raman lidars and cloud Doppler radars, allow us to

obtain vertical profiles of aerosol, water vapor and cloud properties below, inside

and above these clouds with high vertical and temporal resolution.

In this work, observations of thin liquid clouds performed in the period 2010-2013

using multi-wavelength Raman lidars, a cloud Ka-band Doppler radar and a

microwave radiometer operating at CNR-IMAA Atmospheric Observatory (CIAO –

40.60N, 15.72E, 760 m a.s.l.), located in Potenza, Southern Italy, are considered.

Particular attention is devoted to the observation of “broken clouds”, defined as

groups of clouds separated by free cloud regions. These clouds are particularly

interesting because they allow us to study the variability of aerosol optical

properties and relative humidity (RH) in the transition from the cloudy to the

cloudless region.

In this work, a methodology to characterize this variability and to gain a better

insight into droplet activation process is proposed. Through this methodology

several cloud properties, such as the vertical extension of the activation region,

the height and temperature of cloud base and cloud top, the cloud layer thickness

and liquid water path (LWP), are estimated.

Statistics over a selected dataset will be presented, including the correlation

between thermodynamic properties of atmosphere, aerosol type and

updrafts/downdrafts retrieved using a Doppler radar.

P4.12 Continuose Observations of Anthropogenic VOCs at Monte Cimone (Italy):

Trends and Emissions

Jgor Arduini, Eleonora Lo Vullo, Francesco Furlani, Umberto Giostra, Francesco

Graziosi and Michela Maione

Anthropogenic volatile organic compound (VOCs) play a very important role as

primary hazardous air pollutants as well as in the photochemical formation of

tropospheric ozone, peroxycarboxylic nitric anhydrides, formaldehyde and

secondary organic aerosols. Monitoring and modelling of the spatiotemporal

distribution of these species is important for better understanding atmospheric

processes affecting both climate and air quality.

43

For this reason, speciated VOCs and carbon monoxide (CO) continuose

measurements are carried out at the WMO-GAW global station at Monte

Cimone, a background site in proximity of the highly polluted Po Basin in Northern

Italy. In this study we have analysed four-year (2010-2013) time series of C2-C6

alkanes, benzene, toluene, ethyl-benzene, xylenes and CO in order to derive

trends and seasonal cycles, to identify emission sources and to study the impact

of such emissions on the oxidation chemistry.

As observed in other European sites, the VOCs atmospheric mixing ratios

measured at Monte Cimone showed a decline over the study period. We used the

correlation between CO and VOCs in order to characterise emission sources. In

addition, we used the seasonality in the ratios of isomeric alkane pairs (butanes

and pentanes) in order to assess the effects of atmospheric transport. Finally,

concentration ratios of VOCs with different rates of removal have been used as

indicators of photochemical processing.

P4.13 Comparison of spheres and spheroids particles on the closure studies for

microphysical-optical properties

M. Sorribas, F. J. Olmo, A. Quirantes, M. Gil-Ojeda and L. Alados-Arboledas

The natural and anthropogenic atmospheric particles alter the Earth’s energy

budget and they are drivers of climate change. To evaluate the influence of

aerosols on the solar radiation a rigorous knowledge of the absorption and

scattering processes is needed. The aerosols rarely exhibit a spherical shape,

being its geometry more complex. In order to carry out studies about the

scattering properties, theoretical calculations are computed using the Mie or the

T-matrix Theories, assuming homogeneous and spherical particles or non-

spherical particles, respectively.

The Mie model and T-matrix code can be also used to clarify the uncertainties

associated with the instrumentation for measuring microphysical and optical

aerosol properties. One example of this application is the study of the uncertainty

of an integrated nephelometer, instrument widely used to measure the aerosol

scattering and backscattering properties. It integrates the scattered light by the

particles from a volume of air ideally over a full range of angles from 0º to 180º.

A systematic uncertainty of the integrating nephelometry technique is that the

light scattered is truncated near-forward and near-backward direction below 7º

and 10º, respectively. This limitation is commonly known as the angular

truncation error. One of the most popular corrections was presented in Anderson

and Ogren (1998), where a parameterization of the truncation correction is

determined by the ratio between full and truncated scattering computed by Mie

Theory. However, this correction has some limitations related to the particle

shape and size range.

In this study we present the results of a field campaign performed to examine

instrumental closure in aerosol optical and microphysical properties with the aim:

(1) to compare the observed and the computed optical properties, using the

spherical and spheroids approximations; and (2) to analyse the angular

truncation correction in terms of sub- and super-micron particles size ranges.

P4.14 Atmospheric boundary layer and ozone-aerosols dynamics under dusty

conditions from saharan intrusions

J.A. Adame, C. Córdoba-Jabonero, M. Sorribas, D. Toledo and M. Gil-Ojeda

44

In the framework of AMISOC (Atmospheric Minor Species relevant to the Ozone

Chemistry) project a campaign was carried out at El Arenosillo observatory

(INTA/ARN station, 37.1º N 6.7º W, 40 m a.s.l., a coastal area in southwestern

Spain), in May-June 2012. The campaign was focused on the impact of Saharan

dust intrusions in both the Atmospheric Boundary Layer (ABL) and ozone-aerosols

dynamics. In-situ and remote sensing techniques for gases and aerosols

measurements as well as modelling analysis were used. Meteorology features on

surface, ABL structure and evolution, aerosol profiling distribution and aerosol-

ozone interaction on surface were analyzed. In particular, two four-day

measurements periods were selected according to non-dusty (clean conditions)

and dusty (presence of Saharan dust) situations for comparison purposes. In both

aerosol scenarios, sea-land breezes were developed in lower atmosphere whereas

differences were found at upper levels. Results show surface temperatures higher

in 3ºC and lower humidity values during dusty respect to non-dusty period;

thermal structure on surface layer (as estimated by instrumentation located in a

100-m tower) shows differences mainly for nocturnal period and less intense

inversions under dusty conditions. The mixing layer during dusty days presented a

thickness of 400-800 m higher than that observed for non-dusty situation. Dust

presence also disturbed the typical daily ABL evolution and vertical stable

conditions were only observed in early evening during intrusions. During the dusty

days aerosol extinction was 2-3 times higher with the dust layer confined

between 1500 and 5500 m height. Back trajectory analysis confirmed its African

origin. On surface, particle concentration was around 3.5 times higher during

dusty events but local ozone did not exhibit any change. In summary, the arrival

of Saharan dust at upper levels presented a clear impact in meteorological

conditions on surface, inhibited the typical daily evolution of the ABL and caused

an increase in aerosol loading both on surface and at upper altitudes; however,

no dust influence was observed in surface ozone levels.

P4.15 Vertical exchange between the boundary layer and the free troposphere:

Effects on aerosol direct and indirect effects.

Freney, E.J, K.Sellegri, E.Asmi, A. Colomb, M.Hervo, C.Rose, D.Picard.

During February 2012, an exceptional cold event was experienced across Europe.

This cold event was due to a large area of high pressure over Eastern Europe.

Using in-situ measurements of aerosol chemical and physical properties at the

puy de Dome station, as well as LIDAR measurements on aerosol vertical profiles

we studied the exchange between the boundary layer and the free troposphere

during this cold event. Temperatures ranged from -10oC to -18oC, and LIDAR

measurements showed that the puy de Dome station was alternatively sampling

clean regional airmasses in the free troposphere (FT), and sampling

anthropogenic emissions from the surrounding area within the boundary layer

(BL). Within the FT, we observed a gradual change in aerosol physical properties

with increases in aerosol mass concentrations of up to 4 times the starting

concentration (Figure 1), as well as increases in the number of larger particles

(>150 nm). Aerosol chemical properties did not show any significant changes but

increases in organic and nitrate particles were observed. This work discusses

these observations as well as their effects on aerosol direct (aerosol optical

properties) and indirect properties (cloud condensation nuclei).

P4.16 Measurements of volatile organic compounds (VOCs) and NOx within ACTRIS at

45

the puy de Dôme research station (France, 1465m a.s.l.) since spring 2011

A.Colomb, V. Jacob, L. Bouvier, J-M. Pichon, H. Perroux, M. Ribeiro, E. Freney, C.

Rose, C. Gaimoz, J. Fleuret, E.Dumas and K. Sellegri

The high altitude puy de Dôme research station is located in central France (45°

46’ N, 2° 57’ E, 1465 m a.s.l.), 16km away from the city of Clermont-Ferrand. This

station has been classified as representative background. At the summit,

meteorological parameters including wind speed and direction, temperature,

pressure, relative humidity and radiation, atmospheric trace gases (O3, NOx, SO2,

CO2, CO), and aerosol physical, optical and chemical properties (particle size,

black carbon, mass,..) are measured since years.

In spring 2011, cartridges sampling program was started to link the observations

of VOC within ACTRIS at the puy de Dôme research station. Selected volatile

organic compounds (VOCs, including a large set of non-methane hydrocarbons

and some terpenes (isoprene, α-pinene and some oxygenated and halogenated

compounds) were measured during a precampaign in summer 2010, and

intensive field campaigns in spring 2011, summer and winter 2011, 2012, 2013.

The analysis of VOCs collected on Tenax/Carbosieve III cartridges was achieved by

using thermo-desorption coupled gas-chromatography with mass spectrometry

(GC-MS). In order to determine the transport pathways of the air masses prior to

arriving at the pdD site, the Hybrid Single Particle Lagrangian Trajectory (HYSPLIT)

model was used. Trajectories were classified according to their predominant

transport direction prior to measurement as either continental (C), marine (M),

marine modified (Mod), Mediterranean (Med), or mixed depending on their

pathways.

The results presented here are discussed in terms of observed levels, diurnal

variability and sources influence of these gaseous pollutants.

Comparisons with other tracers (NOx (with ACTRIS recommendations)., CO, BC,

…), with aerosols (chemical or physical properties) and other parameters

(temperature, air masses origins, planetary boundary layer height,…), are used to

help identifying main parameters influencing VOCs variability. Role of VOCs as

precursors of oxidants and secondary organic aerosols will be discussed.

P4.17 Linking field and laboratory studies on particle formation

H.E. Manninen, K. Lehtipalo, P.P. Aalto, J. Backman, S. Buenrosto Mazon, X. Chen,

J. Duplissy, A. Franchin, J. Hong, N. Kalivitis, J. Kangasluoma, J. Kontkanen, F.

Korhonen, R. Krecji, J. Lampilahti, K. Leino, G. Steiner, R. Väänänen, R. Wagner, D.

Wimmer, T. Petäjä, And M. Kulmala

New particle formation (NPF), starting from molecular cluster sizes, happens

frequently in the atmosphere. These charged and neutral clusters are climatically

important if they grow to sizes when they can act as seed for cloud droplets. The

occurrence of NPF has been observed in all kind of environments where we have

been measuring from continental to marine and from Antarctic to tropical

environments. The ion spectrometers (Neutral Cluster and Air Ion Spectrometer,

NAIS) and the Particle Size Magnifier (PSM) allow starting the aerosol

measurements from the sizes of molecular clusters and nucleating particles (~1-2

nm in mobility diameter). The PSM and NAIS can also be used to resolve directly

46

the particle nucleation rate and growth rate, which are the dominant factors in

determining how much and what kind cloud droplets can be produced via NPF.

Using these instruments together with mass spectrometric methods, one can

solve both the concentration and composition of the nucleating clusters and their

precursor vapours. This approach have been used e.g. on field at the Hyytiälä

SMEAR II station in Southern Finland and during CLOUD laboratory experiments

at CERN. The laboratory and chamber studies are essential to deepen the

mechanistic understanding of the NPF. Our speciality is the comprehensive, long-

term field measurements conducted at the boreal forest SMEARII site. We have

measured both inside the boreal forest and also at different altitudes above the

forest at a tower and on-board an instrumented aircraft, a hot-air balloon and

recently a zeppelin. By comparing atmospheric cluster and particle measurements

from different instruments and different sites we have shown that most of the

sub-3 nm clusters are originally neutral, seen that the appearance of sub-3 nm

clusters is connected to a high probability of NPF events, and learned about the

horizontal and vertical extent of the NPF.

P4.18 Multiple daytime nucleation events at the high altitude station of Chacaltaya

(5240 m a.s.l.), Bolivia

C. Rose, K. Sellegri, F. Velarde, I. Moreno, M. Ramonet, K. Weinhold, M. Andrade,

A. Wiedensohler, and P. Laj

While nucleation may represent one of the major process responsible for the total

aerosol number burden in the atmosphere, and especially at high altitude, the

occurrence of new particle formation (NPF) events are poorly documented in the

literature for high altitude sites. NPF events were detected and analysed at the

highest measurement site in the world, Chacaltaya (5240 m a.s.l.), Bolivia,

between January 1 and December 31 2012, using a Neutral Aerosol and Ion

Spectrometer (NAIS). NPF frequency at Chacaltaya is one of the highest reported

so far (63.9%) and shows a clear seasonal dependency with maximum up to 100%

during the dry season. This high seasonality of the NPF events frequency was

found to be likely linked to the presence of cloud in the vicinity of the station

during the wet season. Multiple NPF events are seen on almost 50% of event

days, increasing the potential of nucleation to be the major contributor to the

particle number concentrations in the upper troposphere. The median particle

formation rate computed for first position events is

increased during the dry season (1.90 cm-3s-1) compared to the wet season (1.02

cm-3s-1), showing that events are more intense, on top of being more frequent

during the dry season. On the contrary, GRs are on average enhanced during the

wet season, which could be explained by higher amount of biogenic volatile

organic compounds transported from the Amazon rainforest. The NPF events

frequency is clearly enhanced when air masses originate from the oceanic sector,

with a frequency of occurrence close to 1. However, based on the growth rate of

the largest particle size range, we calculate that particles most likely nucleate

after the oceanic air masses reach the land and are presumably not originating

from the marine free troposphere. Our observations at CHC suggest that

nucleation and growth are likely to be the major mechanism feeding the upper

atmosphere with aerosol particles.

P4.19 Direct observation of neutral clusters' contribution to new particle formation in

the free troposphere

47

C. Rose, K. Sellegri, E. Asmi, M. Hervo, E. Freney, H. Junninen, J. Duplissy, M.

Sipilä, J.Kontkanen, K. Lehtipalo and M. Kulmala

The formation of new aerosol particles (NPF) in the atmosphere is a key process

influencing the aerosol number concentration as well as the climate, in particular

in the free troposphere (FT) where the newly formed particles directly influence

cloud formation. However, free tropospheric NPF is poorly documented due to

logistic limitations and complex atmospheric dynamics around high altitude

stations that prevent the observation of daytime processes such as NPF in the FT.

Recent improvements in measurement techniques make now possible the

detection of neutral clusters down to ~1-nm sizes, which opens new horizons in

our understanding of the nucleation process. Indeed, only the charged fraction of

clusters have been reported in the upper troposphere up to now. Here we report

observations of charged and neutral clusters (1- to 2.5-nm mobility diameter)

during unusual day-time free tropospheric conditions at the altitude site of Puy de

Dôme (1465m a.s.l.), central France, between 10th and 29th February, 2012. Our

findings demonstrate that in the free troposphere, the formation of 1.5-nm

neutral clusters is about 40 times higher than the one of ionic clusters during NPF

events, indicating that they dominate in the nucleation process. We also observe

that the total cluster concentration increases by a factor of 5.5 during NPF events

compared to the other days, which was not observed for the charged cluster

population in the past. In the FT, the

nucleation process does not seem to be sulphuric acid-limited, as previously

suggested, and could be promoted by the transport of pollutants to the upper

troposphere.

P4.20 ACSM measurements and organic tracers at Montseny during summer EMEP

campaign

María Cruz Minguillón, Anna Ripoll, Barend van Drooge, Xavier Querol and

Andrés Alastuey

The forested regional background ACTRIS site of Montseny (MSY, 41°46'46"N

02°21'29"E, 720 m a.s.l.) was chosen for the present study. It is located in

Northeast Spain, 50 km away from Barcelona, in the Western Mediterranean

Basin. The atmospheric dynamics is regulated by complex climatic and orographic

effects which control the concentration, composition and transport of PM.

An Aerosol Chemical Speciation Monitor (ACSM, Aerodyne Research Inc.) was

deployed at MSY from June 2012 to July 2013, according to the ACTRIS schedule.

The ACSM measures non-refractory submicron aerosol distinguishing organic

aerosol (OA), nitrate, sulphate, ammonium and chloride (Ng et al., 2011). The

ACSM was set to measure with a time resolution of approximately 30 min.

Positive Matrix Factorization (PMF), and complementarily Multilinear Engine

(ME2), of the organic mass spectral data matrix was carried out, providing

information on different sources or types of the OA, such as hydrocarbon-like OA

(HOA, a surrogate of road traffic emissions), biomass burning OA (BBOA), and

two types of oxygenated OA (OOA, a surrogate for secondary OA) with different

degrees of oxidation.

The results shown will focus on the EMEP summer campaign (June-July 2012).

Among the additional measurements, we highlight the organic compounds

analyzed off-line in 24-h PM1 samples, including tracers such as levoglucosan and

hopanes. These results will be shown together with the resolved organic sources

48

from the ACSM dataset, hence being able to confirm the sources found and the

relative contribution to the bulk organic matter.

P4.21 Analysis of a high level of particulate-pollution event in Paris Megacity by

integrating in-situ and remote sensing aerosol/gas measurement at the SIRTA

ACTRIS Observatory.

J-C. Dupont, M. Haeffelin (IPSL/CNRS); J. Badosa (LMD/CNRS); T. Elias (HYGEOS);

N. Bonnaire, V. Gros, M. Ramonet, J. Sciare, G. Tremoy, F. Vimeux (LSCE); O.

Favez (INERIS); P. Goloub (LOA); T. Bourcy, F.Zanghi (Météo-France)

A high level of particulate-pollution event has been observed in Paris Megacity

between 6 and 15 March 2014. The SIRTA Observatory has documented all

atmospheric variables between surface and the top of free troposphere with in-

situ sensors and active/passive remote sensing instruments.

We will describe the instrumental dataset (more than 150 instruments),

meteorological conditions and variability of some species, such as (i) aerosol

(particle mass, chemistry, size distribution and absorption/scattering), (ii) reactive

gas (type, chemistry), (iii) radon and GES and (iv) isotopic species (CO2, CH4 and

H2O).

A specific attention will be given in this presentation to understand the processes

responsible for the high concentration level of thin particles (smaller than 2.5µm

with a medium radius around 0.2µm) in a thin mixing layer (night 200m and day

600-1200m). All these collocated measurements on the Saclay plateau (ACTRIS

platform) is an ideal place to conduct this work. In fact, the chemical analysis

shows that the major part of these particles were secondary aerosols related to

anthropogenic activities such as traffic, wood burning and agriculture. And, the

geochemical tracers, active and passive remote sensing instruments (lidars, cloud

radar, microwave radiometer and sun-photometer) allow us to characterize the

mechanisms leading to this so high particle pollution: (i) role of boundary layer

dynamics (stable, neutral, convective), (ii) role of geographical origin of PM

components (local, regional, European) and (iii) role of liquid phase (fog and

boundary layer cloud). Finally, the impact on solar and ultra-violet downwelling

fluxes will be quantified.

P4.22 Fine and coarse dust separation with polarization lidar

R.-E. Mamouri, A. Nisantzi, D. Hadjimitsis, and Albert Ansmann

A new lidar profiling method is developed that allows us to separate height

profiles of particle backscatter and extinction coefficients, volume, and mass

concentration of fine-mode dust, coarse-mode dust, and the remaining non-dust

aerosol component (haze, smoke, marine). The method is based on measured

profiles of the particle depolarization ratio with polarization lidar and makes use

of fine-mode (particle radius < 500 nm, 14-17%) and coarse-mode dust

depolarization ratios (radius > 500 nm, 39%), measured in the laboratory by Sakai

et al. (Appl. Opt., 2010). The new method enables us to determine the

contribution of mineral dust to the PM1.0 aerosol burden. Furthermore, such size-

resolving observations are very useful to check the potential of dust transport

models to properly describe the emitted dust size distribution, and therefore the

dust cycle and related radiative effects. Recent publications (Kok, ACP, 2011,

Zhang et al., GRL, 2012) suggest that the dust size distribution is controlled by

processes described by the brittle fragmentation theory. These distributions

strongly differ from size distribution parameterizations used in most global

49

circulation models. This aspect has strong implications on dust cycle and

deposition modelling. The new lidar technique is applied to a period with complex

aerosol layering of fine-mode background dust from Turkey and Arabian desert

dust from Syria. The observation was performed at the combined

EARLINET/AERONET site of Limassol, Cyprus, in September 2011. The dust

profiling methodology and case studies are presented. A consistency study based

on simultaneous observations with EARLINET lidar and AERONET photometer

demonstrate the applicability of the new lidar technique. Good agreement with

AERONET column aerosol observations was found.

P4.23 The Madrid (MAD) station: vertical and ground based measurements of

chemical, physical and optical properties of aerosols

B. Artíñano, F. J. Gómez Moreno, E. Coz, L. Núñez, M. Palacios, A.J. Fernández, E.

Alonso, P. Salvador, M. Becerril, M. Pujadas, A.S.H. Prevot, M. Laborde, S.N.

Pandis

Physicochemical properties of ambient aerosol and atmospheric parameters are

real-time monitored at the CIEMAT research station in Madrid. The site is located

in a sub-urban area northwest the Madrid city. Anthropogenic (typically urban, as

no significant industry is located in the vicinity of the Madrid area) and natural

(mineral dust, biogenic) sources determine the characteristics of the air mass

pollution at this site. Long-range transport processes (European polluted air mass,

African dust outbreaks) have also influence on specific conditions. Urban aerosols

are continuously documented through a number of ground-based measured

parameters: size distribution (SMPS), hygroscopic growth factor (HTDMA),

hygroscopic scattering enhancement (dry-ambient Aurora1000/3000

nephelometers, ACS1000), light absorption and sizeselected BC concentrations

(Aethalometers AE33 and AE31), non-refractory chemical composition (ACSM).

Vertical profiling of tropospheric aerosol and water vapour are obtained at the

site through a LIDAR-Raman instrument integrated in EARLINET (#21 lidar

station). Meteorological parameters and gaseous pollutant concentrations at this

site are provided by a meteorological station (52 m mast) and an active DOAS

system, respectively. In the absence of external inputs, carbonaceous aerosol is

dominant in Madrid. Increasing BC concentrations (about 40% on average of the

PM1), mostly from fossil fuel from traffic and partly from heating systems, seem

to inhibit the hygroscopic growth, partially conditioned by the phase distribution

within the aerosol structure. This enhancement is moderate at high RH, even

during periods of high concentrations of inorganic compounds, which is typical

from polluted areas. A number of aerosol shrinkage processes have been

characterized by the SMPS during nucleation events linked to an increase of wind

speed during the growth phase of the new particles. They mostly occur during

spring and summer periods.

P4.24 Comparison of the aerosol size distribution retrieval from a sun photometer

with in situ measurements at high altitude: taking into account the effect of

water uptake.

Chauvigné Aurélien, Montoux Nadège, Freville Patrick, Hervo Maxime, Sellegri

Karine

Aerosols influence the Earth radiative budget through scattering and absorption

of solar radiation and it is significantly affected by ambient humidity. Several

methods are used to retrieve aerosol properties and thus quantify their direct and

50

indirect impacts on climate. At the Puy de Dôme station, the co-located in situ

measurements at high altitude with parallel remote sensing instruments give

opportunities to evaluate the accuracy of remote sensing retrievals of the aerosol

size distributions. The size distribution retrieve by the Aerosol Robotic Network

(AERONET) Sun photometer observations are compared to the in-situ size

distributions, dry and at ambient relative humididy during a one year period

filtered from cloudy and multi aerosol layers events detected using the LIDAR

backscattering profiles. The hygroscopic growth factors (HGF) were derived by

seasonally segregated parameterization performed over a 4-year period

(Holmgren et al. 2014), and applied to the in situ size distributions. For wet and

dry cases, the sun photometer clearly underestimates diameters for the

accumulation mode and overestimates concentrations for both accumulation and

coarse modes. It appears that the sun photometer underestimation of the aerosol

size is actually higher when the real (wet) size of the aerosol is taken into account.

P4.25 Simulation of improved daytime capabilities of lidar instruments

F. Madonna, A. Amodeo, U.Wandinger

So far, most of the multi-wavelength Raman lidar observations of aerosols are

performed at night, because Raman signals are weak compared to daylight

background. Different techniques have been developed to improve Raman lidar

daytime capabilities in the past years. Indeed, the retrieval of aerosol extinction

during daytime is feasible through the detection of backscattered radiation due to

the pure Rotational Raman Spectrum (PRRS) of molecular nitrogen or oxygen,

much brighter than the vibration-rotation spectrum.

The existing techniques for the measure of PRRS are based on small-bandwidth

emitter and receiver systems and on a small receiver field of view to suppress the

daylight background. They have been successfully tested and implemented in a

few systems which are already in operational use within EARLINET (European

Aerosol research Lidar NETwork).

In this work, several different configurations used as receiver for a lidar system

detecting the PRRS in daytime conditions are compared by means of numerical

simulations. The configurations are mainly differentiated by the design of the

spectral selection unit implemented in the receiver of each lidar system, based on

a narrow-bandwidth filters, grating spectrometers, and hybrid solutions. The

research of configurations able to be more easily implemented on a large number

of lidar systems within ACTRIS are explored.

To improve Raman lidar daytime capabilities, it is also required the use of

receivers able to minimize the region close to the ground level where the lidar

signals are affected by the incomplete overlap between the lidar source and the

receiver FOV, that creates problems to the retrieval of aerosol optical properties.

In addition to this incomplete overlapping problem, the laser signal backscattered

from the close range is not focused on the focal plane of the telescope. In order to

select the best option for the detection of PRRS in the close range (altitudes lower

than about 400-500 m), different telescope options (reflectors and refractors)

have been compared with respect to the potential problems affecting the lidar

measurements in this observation range.

P4.26 Measuring aerosol and water clouds with Raman-Lidar RAMSES

Andrew Reigert, Jens Reichardt

The RAMSES-lidar at the German Meteorological Service’s observatory in

51

Lindenberg was originally designed as a nighttime water vapor measurement

system. It has since outgrown its original purpose and now measures all relevant

lidar parameters, also during the day. It measures water vapor (Raman), nitrogen

(Raman) and elastic backscatter in both near-range receiver and far-range

receiver. In addition the far-range receiver has 2 temperature channels (Raman)

and 2 depolarization channels. At the single emitter wavelength of 355 nm

products such as particle backscatter coefficient, particle extinction coefficient,

lidar ratio and particle depolarization ratio are calculated to characterize clouds

and aerosol.

The water-vapor mixing ratio is calculated from the water vapor channel. The

mixing ratio is then used to calculate the water vapor pressure. Given a

corresponding temperature profile, either from rotational-Raman-, radiosonde- or

microwave radiometer measurements, the water vapor saturation pressure is

calculated. The ratio then provides the relative humidity.

Measurements are done with a high temporal (30 s) and vertical resolution (7.5

m). Depending on measurement quality, signal ratio products (e.g. backscatter

ratio) can be analyzed at full measurement resolution. For other products the

resolution of statistically independent grid points at a height of 4 km can still be

as high as 300 s and 75 m.

All these features make RAMSES uniquely suitable for measuring aerosol

properties very close to the cloud base and thus for studying aerosol-cloud

interactions. Because of the water vapor measurement capability it is possible to

study the effects of increasing relative humidity on aerosol optical properties. The

high measurement resolution makes it possible to measure small scale convective

boundary layer clouds.

Currently, RAMSES has been moved into a new lidar facility, and instrument

improvements are being implemented. It is expected that RAMSES will be fully

operational again in early summer, and that more measurement cases of aerosol-

cloud interactions can be added to the existing data set.

P4.27 8 years of equivalent black carbon observations at GAW/WMO Monte Cimone

station, an analysis of the main contributions affecting its variability

Marinoni A., P. Cristofanelli, D. Putero, T. Landi, L. Bourcier, R. Duchi, M. Busetto,

F. Calzolari, P. Bonasoni

The Mediterranean basin is recognized as a hot-spot region for climate change

and air-quality: it represents a major crossroad for different air mass transport

processes. In particular, large amounts of anthropogenic pollutants emitted in

continental Europe are transported towards the Mediterranean basin especially

during summer, when intense vertical transport is favored by the meteorological

conditions. Moreover, the Mediterranean basin is also affected by large wildfire

events occurring in Europe and in other continents.

Black carbon is one of the most discussed climate forcers, the unique particulate

pollutant acting as “warmer” in the climate system, having also a relatively short

lifetime, thus a faster climate response after emissions reduction. It is emitted

both by anthropogenic sources and natural/anthropogenic biomass burning.

Equivalent black carbon (eqBC) is measured since 2005 at global WMO/GAW

station of Monte Cimone (2165m asl), a sampling site considered representative

of the background conditions of the Southern Europe/Mediterranean Basin.

Atmospheric observations at Monte Cimone are frequently representative of the

free troposphere even if, especially during summer, this measurement site can

52

provide direct information about the injection of anthropogenic pollutants to the

free troposphere of the Mediterranean basin. In this work, we analyzed the

variability of eqBC at Monte Cimone over 8 years of data. To specifically assess

the vertical export of absorbing material from the Po valley to the free

troposphere, we coupled Monte Cimone summer observations with BC

measurements collected in the Po Basin.

Moreover, for evaluating the possible contribution of open vegetation fires to the

variability of eqBC in the Mediterranean area, we coupled satellite observations

(MODIS fire products and land cover type) and deterministic modeling systems

(i.e. Hysplit, WRF). The attempt of separating the different contributions (i.e.

anthropogenic pollution coming from the Po valley and those coming from

natural sources) to the high eqBC concentrations at Monte Cimone was also

carried out.

P4.28 Long-term investigation of Saharan dust transport events at the Mount Cimone

GAW Global Station, Italy (2165 m a.s.l.)

R. Duchia, L. Bourciera, P. Cristofanellia, A. Marinonia, D. Puteroa, T.C. Landia, F.

Calzolaria, M. Busettoa, U.Bonafèa and P. Bonasonia

Due to the high vulnerability to climate change and temperature rise predictions

higher than the global average, Mediterranean basin and Southern Europe are

key areas in understanding long-term regional climate change. They are

frequently interested by the presence of desert dust aerosol transported from

North Africa which plays an important role in climate and environmental system.

Mt. Cimone (2165 m a.s.l., 44°11’N, 10°42’E) is the highest peak of the Italian

northern Apennines and represents the first mountain ridges that Saharan air

masses encounter during their northward displacement towards Europe and

Alpine ranges. Dust transport events (DTEs) have been identified since 2002 at the

CNR baseline global GAW station of Mt. Cimone (CMN) when the atmospheric

concentration of coarse particle (1 μm ≤ Dp≤ 20 μm) significantly increased with

air-masses coming from North Africa as deduced by back-trajectory simulations.

The FLEXTRA three-dimensional back-trajectories analysis also permitted a

statistical climatology of the optical and microphysical properties of the aerosol

according to the origin of the air masses.

Over the investigated period, 15% of time at CMN appeared to be influenced by

dustevents, with maximum of occurrence in spring and summer. Inter-annual

variability of DTEs frequency and magnitude were analysed as a function of

atmospheric transport patterns and climate indexes (e.g. NAO, MEI).

With the aim to investigate the impact of dust transport on aerosol optical

properties over the Mediterranean basin, the absorption and scattering

coefficients during DTEs have been analysed on a seasonal basis. Both scattering

and absorption coefficients clearly showed an increase of the optical capability in

presence of dust, even if on a seasonal basis this increase appeared to be

statistically significant only for spring. While coarse and accumulation particle

number showed significant increases during the identified DTEs, the total aerosol

particle number concentration (10 nm<Dp<3μm) decreased on average.

P4.29 NanoMap: Geographical mapping of atmospheric new particle formation

through analysis of particle number size distribution and trajectory data

Adam Kristensson, Martin Johansson, Erik Swietlicki, Niku Kivekäs, Tareq Hussein,

Tuomo Nieminen, Markku Kulmala, and Miikka Dal Maso

53

New particle formation, potentially responsible for up to 50 % of global cloud

condensation nuclei production, is not monitored all over the world. How often

new particle formation occurs over remote places, and ocean areas is especially

poorly characterized. To remedy this situation, a method has been developed to

map new particle formation up to 500 km away from a field site using only

particle number size distribution and meteorological back trajectory data as

input. Namely, by studying the particle number size distribution at a specific field

site it is possible to observe how newly formed particles in the nanometer size

range are growing by condensation until they reach the size of several tens of

nanometers. The grown particles have been formed as 1.5 nm particles at a

certain distance upwind of the field site, and this place of origin can be traced

with the meteorological back trajectories. An open-access freeware program has

been developed for this analysis. It is called NanoMap, and it has been tested over

the Finnish ACTRIS supersite Hyytiälä. NanoMap shows that new particle

formation at 1.5 nm diameter frequently occurs all over the Finnish continent.

However, it also shows that it occurs over the Baltic Sea, although it is slightly less

frequent than over the Finnish continent for some of the wind directions.

NanoMap can be used at many other sites, and is currently being tested at 2

other ACTRIS supersites, Vavihill and Finokalia in Sweden and Greece,

respectively.

P4.30 Aerosol optical depth changes over Poland, preliminary results and

perspectives

A. Pietruczuk, A. Szkop, M. Posyniak

Atmospheric aerosol is an important factor in climate studies. Besides of that,

measurements of its optical properties are rather sparse in Poland. Long term

observations of aerosol optical properties are conducted at Geophysical

Observatory at Belsk as well as by PoalndAOD network started in 2011. Belsk’s

observatory is placed in a rural region and equipped with sun photometers,

Brewer spectrophotometer and a LIDAR. The LIDAR system is being upgraded to

obtain 3+1 system in far range and 3+2 system in close range.

In this work preliminary results of modification of aerosol optical depth (AOD)

during transport over Poland will be presented. Sunphotomeric data from

AERONET stations located in Belarus, Germany and Sweden as well as satellite

data were used to study changes of AOD between Belsk and chosen stations.

Frequency plots of investigated differences have two modes. One concentrated

around zero and the second one shifted to positive values. This second mode is

related to aerosol accumulation over urban/industrial regions located mainly

south and west of Belsk.

Preliminary results of the trajectory analysis based on HYSPLIT model suggest that

a significant portion of an aerosol inflow over Poland originates in the southern

neighboring countries including Czech Republic, Hungary and Slovakia. To enable

studies of the changes occurring in aerosols during their transport over Poland a

new atmospheric observatory is being prepared in a south-western Polish city of

Raciborz at a site of IGF’s seismological station. The new installation is being

designed to be fully automatic when completed with the main instruments

including a sun-tracking photometer and a single wavelength autonomous elastic

lidar (a ceilometer).

P4.31 Recent science from Auchencorth: Insights into PM events and pollutants

54

associated with them

MM Twigg, J Kentisbeer, M Coyle, SR Leeson, A Hoque, YS Tang, MR Jones, B

Langford, WJ Bealey, D Leaver, I Simmons, I Washbourne, M Vieno, CF Braban, E

Nemitz

Auchencorth Moss has a hourly resolution measurement of PM10 and PM2.5

inorganic composition, NH3, HCl, SO2 HNO3 and HONO trace gases and PM size

distribution. When combined with the measurements of trace gases the PM

measurements can lead to insights into the drivers of chemical composition and

long term average concentrations which are comparable with modelling work, for

example with EMEP4UK. Recently published mercury data are discussed in

relation to the PM measurements. A particular new focus is looking at how

episodic pollution events occur and how they are interpreted. Results from

intensive measurement carried out in 2012 plus some event studies are

presented. The first assessment of fluoride in rain measurements carried out as

part of the routine measurements will be presented.

P4.32 Long-term study of new particle formation In a coastal environment:

Meteorology, gas phase and solar radiation implications

Sorribas, M., Adame, J.A., Vilaplana, J.M., Córdoba-Jabonero, C., Olmo, F.J.,

Alados-Arboledas, L. and Gil-Ojeda, M.

New particle formation (NPF) has been investigated at a coastal background site

in the South-western Spain over a 4-years period, using a Scanning Particle

Mobility Sizer (SMPS). The goals were to characterize the NPF and to investigate

their links with meteorological, gas phase (O3, SO2, CO and NO2) and solar

radiation (UVA, UVB and global) for event and non-events days. A methodology

to identification and classification of the NPF was implemented, being inputs the

wind direction and modal concentrations. NPF events showed a frequency of 24%

on total days. The mean duration was 9.2±4.2 hours. Contrary to previous studies

in other locations, the NPF frequency reached its maximum in cold seasons

around 30% of the days, and the lowest was in July with only a 10%. The seasonal

wind pattern was the most important parameter controlling the NPF frequency.

The mean formation rate was 2.2±1.7 cm-3 s-1, showing maxima in the spring

and early autumn and minima during the summer and winter. The mean growth

rate was 3.8±2.4 nm h-1 with higher values from spring to autumn. The mean

formation and growth rates and theirs seasonal evolutions are in agreement with

previous observations at continental sites in Northern Hemisphere. A NPF

classification in different Classes was carried out to explore the effect of synoptic

and regional-scale patterns on particle formation and growth. Results show that

under breeze regime, the temperature indirectly affects the NPF events. Higher

temperature increases the strength of the breeze recirculation favouring the

gases accumulation and subsequent NPF appearance. Additionally, the role of

high relative humidity inhibiting the NPF was evinced during synoptic scenarios.

The remaining meteorological variables (RH), tracers gases (CO and NO), solar

radiation, PM10 and condensation sink had a moderate or high connection with

both formation and growth rates, depending on the Class event.

P5.33 Comparison of EC, OC and OCx fractions at Prague-Suchdol and Košetice

background sites during heating and non-heating season

Petr Vodička, Jaroslav Schwarz, Vladimír Ždímal

55

Parallel measurements of elemental and organic carbon (EC and OC)

concentrations in the atmospheric aerosol were performed at the Czech

background site Košetice (rural environment) and at Prague-Suchdol urban

background site during heating (15 February – 1 April 2010) and non-heating (27

May – 30 July 2010) seasons. Semi-online field OC/EC analyzers (by Sunset

Laboratory Inc.) were used for the measurements with two hour time resolution.

The results show seasonal and sites differences in the content of EC and OC.

Overall, the highest concentrations of both the EC and OC were found during the

heating season at the suburban site. Non-heating season gives similar

concentrations of the OC on both sites, however, slightly higher concentrations of

EC were measured at suburban site, probably due to higher traffic. Diurnal

variations well indicate rush hour peak of the EC at suburban site during both

measurement periods, while EC time trends at rural background site show almost

no characteristic peaks.

Moreover, an analysis of four OC fractions and pyrolytic carbon (PC) depending

on the volatility (OC1 – most volatile, OC4 – least volatile) was carried out.

Diurnal trends of OC fractions in winter show significantly higher concentrations

of the OC1, OC4 and PC fraction at suburban site, however, urban OC1-OC4

concentrations in summer are much more similar to rural site. Therefore, detailed

analyses of OC fractions demonstrate the significant anthropogenic effect of

specific OC fractions on urban environment.

13:00-14:30 Lunch break

ACTRIS General Assembly I

Thursday, 12 June, 14:30 – 15:30

15:30-16:00 Coffee break

ACTRIS General Assembly II

ACTRIS SSC-AB

Thursday, 12 June, 16:00 – 18:00

Oral session S5: Climatology and Trends

Friday, 13 June, 09:00 – 09:30

09:00-09:30 ACTRIS-2

Presentation of the project & discussion (part II)

G. Pappalardo / P. Laj

Friday, 13 June, 10:00 – 12:00

Chairs: Anthony Illingworth, Cathrine Lund Myhre

Keynote presentation

(9:30-10:00)

AERONET program

Brent Holben (NASA-GSFC, USA)

S5.O1 (10:00-10:15) Long-term aerosol number size distribution measurements in Eastern

56

Mediterranean Nikolaos Kalivitis, Giorgos Kouvarakis, Aikaterini Bougiatioti, Iasonas Stavroulas, Alfred Wiedensohler and Nikolaos Mihalopoulos

Aerosol number size distributions have been measured at the environmental

research station of University of Crete at Finokalia, Crete, Greece (35˚20΄N,

25˚40΄E, 250m a.s.l) on a continuous base since 2008 in the frame of EUSAAR and

ACTRIS projects. The Finokalia station is the only station in Eastern Mediterranean

that size distribution measurements are taking place on a continuous basis during

both projects and is considered as a reference station for the region. The Eastern

Mediterranean is a cross-regional hotspot and its atmosphere is a complex

environment affected greatly both by long range transport processes from

different aerosol sources surrounding the region, namely marine, anthropogenic

from continental Europe and desert areas from northern Africa and from local

processes greatly affected by Intense photochemistry and sea-atmosphere

interactions. Longstanding monitoring and characterization of atmospheric

aerosols at Finokalia are of great importance for the whole region.

S5.O2 (10:15-10:30) Identification and monitoring of Sahara dust: An inventory representative for central Europe since 1997

H. Flentje, C. Beck, M. CollaudCoen, J. Cyrys, J. Gu, and W. Thomas

A daily catalogue of Sahara dust (SD) events at the Hohenpeißenberg Global

Atmosphere Watch (GAW) station (47.8°N, 11.0°E, 980 m a.s.l.) is presented from

15 years in-situ surface aerosol measurements. We identify Sahara dust particles

from the chemical composition, particle volume distribution and optical

properties of ambient particles. The detection skill is evaluated with data sets

from neighboring stations and aerosol model analyses and is comparable to that

of a Positive Matrix Factorization.

High daily Ca2+ concentrations combined with enhanced alkalinity and large

coarse particle mode volumes are identified as specific indicators for SD

admixture in Central Europe, while the specificy of spectral absorption is

unexpectedly small. On average, SD is detected in 5 to 15 Sahara dust events

(SDE)/yr covering about 10-40 days/yr in the boundary layer (BL). The frequency

of SDE is height-independent in the BL but the signature becomes less clear at

lower levels. It exhibits a clear seasonality with maxima in spring and autumn but

no significant long-term trend. With a total 228 SD days observed in the lower BL

from 1997 to 2012, 78/96/42/19/9/4/2 SDE lasted for 1/to/7 consecutive days.

On only 139/122/88/37 of 241 days, the SDE at Hohenpeißenberg extended as far

as to the 250 km distant Swiss Jungfraujoch station. Wet deposition of Ca2+ at

the surface is weakly correlated (R2=0.06) with the SDI and yields an average

annual Ca2+ imission of 0.22±0.04 g/m²yr, about 40% of which is due to SD. The

majority of outstanding weekly iron and aluminium depositions are associated

with SDE. The contribution of Sahara dust to the average PM10 load accounts to

0.5±0.1 µg/m³ (» 5%), but all threshold exceedances according to European

legislation (daily PM10 > 50 µg/m³) at Hohenpeißenberg are due to Saharan dust.

10:30-11:00 Coffee break

S5.O3 (11:00-11:15) Troposphere aerosols and long-term variations of cloud covering at Abastumani Goderdzi Didebulidze and Maya Todua

In Caucasus region, like other locations, the aerosols in troposphere and lower

stratosphere are both of local origin and a result of global transfer. Periodically

57

there are observed dust intrusions from other regions like Sahara, as well as

volcanic eruptions and forest fires. The lower atmospheric circulation in Caucasus

has its own peculiarities. Aerosols, if not accompanied by rain, are promptly

transported through the region. Abastumani is one of the favorable observation

locations, almost free from anthropogenic pollution. We studied long-term inter-

annual distributions of clear days and nights in Abastumani from continuous

atmospheric observations during 1957-1993. The data demonstrated that the

maximum number of cloudless days occur in August, while for cloudless nights it

appears in September, which maybe is unusual since aerosol concentration in

August is quite high. During geomagnetic disturbances, occurring mostly at

maximum solar activity phase, the greatest number of cloudless days moves to

September, which indicates the influence of cosmic factors on cloud covering. The

observed long-term trends of the mean seasonal planetary geomagnetic Ap index

for cloudless days and nights in summer also suggest the cloud cover coupling

with climate change. The comprehensive study of meteorological parameters and

lidar data in this region should be important for understanding regional and

global peculiarities of current climate change.

S5.O4 (11:15-11:30) Long term trends in aerosol optical characteristics in the Po Valley (IT) J.P. Putaud, F. Cavalli, S. Martins dos Santos, and A. Dell’Acqua

Aerosols properties have been monitored by ground-based in-situ and remote

sensing measurements at the station for atmospheric research located in Ispra on

the edge of the Po Valley for almost one decade. In-situ measurements are

performed according to Global Atmosphere Watch recommendations, and quality

is assured through the participation in regular inter-laboratory comparisons.

Sunphotometer data are produced by AERONET. Data show significant decreasing

trends over 2004 – 2010 for a number of variables including particulate matter

(PM) mass concentration, aerosol scattering, backscattering and absorption

coefficients, and aerosol optical thickness (AOT). In-situ measurement data show

no significant trend in the aerosol backscatter ratio, but a significant decreasing

trend of about -0.7 ± 0.3% in the aerosol single scattering albedo in the visible

light range. Similar trends are observed in the aerosol single scattering albedo

retrieved from sunphotometer measurements. Correlations appear between in-

situ PM mass concentration and aerosol scattering coefficient on the one hand,

and elemental carbon (EC) and aerosol absorption coefficient on the other hand,

however, no increase in the EC/PM ratio was observed, which could have

explained the decrease in SSA. The application of a simple approximation to

calculate the direct radiative forcing by aerosols suggests a significant diminution

in their cooling effect, mainly due to the decrease in AOT. Applying the

methodology we present to those sites where the necessary suite of

measurements is available would provide important information to inform future

policies for air quality enhancement and fast climate change mitigation.

S5.O5 (11:30-11:45) Validation of CALIPSO Level 2 aerosol profiles by EARLINET correlative measurements L. Mona, N. Papagiannopoulos, G. D’Amico, A. Giunta, A. Hiebsch, U. Wandinger, A. Apituley, L. Alados-Arboledas, D. Balis, A. Chaikovsky, A. Comeron, F. De Tomasi, V. Freudenthaler, I. Grigorov, M. Iarlori, H. Linnè, F. Madonna, A. Amodeo, A. Papayannis, A. Pietruczuk, F. Schnell, N. Spinelli, M. Wiegner and G. Pappalardo

58

EARLINET provides long-term, quality-assured aerosol data offering a unique

opportunity for the validation and exploitation of satellite-based aerosol

measurements. In particular, CALIPSO has been providing global aerosol/cloud

vertical profiles since June 2006. As long-term lidar network on continental scale,

EARLINET is the best candidate for the validation of aerosol and clouds

measurements provided by space lidars.

The good performance of CALIPSO and the absence of evident biases in the

CALIPSO raw signals were demonstrated through devoted comparison with

EARLINET ground based data applying an ad-hoc methodology. Case studies

analysis showed that the aerosol optical properties provided by CALIPSO (i.e.

Level 2 products) are typically in agreement within errors and uncertainties with

EARLINET measurements. In cases of high dust load, the aerosol extinction

retrieval can be affected by the influence of multiple scattering on space borne

lidar measurements. From Level 2 aerosol profiles, monthly mean profiles of the

aerosol extinction evaluated on 5° longitude x 2° latitude grid are provided as

Level 3 data. Once validated and assessed, these profiles would provide a suitable

database for climatological studies and comparison/assimilation in climate

models.

For this aim, all EARLINET observations related to CALIPSO overpasses collected

since June 2006 are compared to corresponding CALIPSO Level 2. This study

furthermore benefits from the availability of the 12-years long-term database of

EARLINET climatological data. About 150 profiles are compared. Apart from cloud

affected cases, we have on average a good agreement in backscatter profiles

comparison (Lev2) for all the stations. While larger discrepancies are observed for

extinction profiles. These can be related to the difference between the lidar ratio

values used in the CALIPSO retrieval and the measured ones. In particular,

significant differences are observed for mixed dust (Central Mediterranean area ),

polluted particles (Naples big city) and marine aerosols (Evora coastal site).

S5.O6 (11:45-12:00) Long-term surface ozone and aerosol physical variability at the Mt. Cimone WMO/GAW Global Station (2165 m a.s.l., Italy) L. Bourcier, P. Cristofanelli, A. Marinoni, R. Duchi, D. Putero, T.C. Landi, F.

Calzolari, M. Busetto, U.Bonafè and P. Bonasoni

Ozone (O3) and aerosol particles have a substantial impact on climate system and

air quality, especially over the Mediterranean basin where anthropogenic and

natural emissions as well as transport processes can significantly affect their

variability.

Surface O3 is monitored since 1991 at the global GAW station of Mt. Cimone

(CMN, 44° 11’ N, 10° 42’ E), while microphysical properties of aerosol particles

(scattering and absorption coefficients, number concentrations) are continuously

measured since 2008. Its location in the Mediterranean region, its physical

characteristics (highest peak of the Italian northern Apennines, 2165m a.s.l.),

makes it particularly suitable to study both the background conditions of the

Mediterranean/South Europe.

We analysed the long-term surface O3 variability at CMN from 1991 to 2011. The

measurements performed at this high-mountain observatory represent the

longest surface O3 record at a baseline site in the Mediterranean basin. Clear

positive linear trends in the monthly O3 mixing ratios were detected over the

period 1991 – 2011 with significant decreases of the seasonal O3 growth-rates.

Concerning the aerosol physical properties, the yearly and seasonal tendencies

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were investigated from 2008 to 2013 and showed a good agreement with the

trends observed at other European stations, even if it is hard to obtain statistically

robust indication for this relatively short time period. The monthly inter annual

tendencies are under investigation.

These information would be useful to better depict the long-term variability of

atmospheric composition of the Mediterranean basin and to better assess the

possible influence of anthropogenic and natural contributions.

Poster session P5: Climatology and Trends

Friday, 13 June, 12:00 – 13:00

P5.1 Winter/ Summer Vertical Aerosol Profiles in the Israeli coast using a

Ceilometer, Aeronet and Models

Smadar Egert, Leenes Uzan, Pinhas Alpert

The Earlinet spatial station spread currently reach Greece and Cyprus as the

eastern Mediterranean side, allowing accurate typing of the aerosol vertical

profiles. In Israel, several studies were done using satellite images and Aeronet

radiometric data that supplies the line integral of the aerosol features. However

Israel is equipped with several Ceilometers that were used for cloud detection and

their raw data was not collected. Although they are single wavelength Lidars,

they are located in various landscapes (near-seacoast, inland, mountain desert).

So access to their raw data is gradually built to monitor the layers features over

Israel and their relative evolution with time, as additional information to the

satellites and radiometric data. This data can serve as additional information to

the sophisticated stations of the eastern border of the Earlinet map (WP2 of the

Actris). Data analysis started last summer using the first available station located

on the middle of the Israeli shore.

The Israeli vertical temperature distribution during Summer was analyzed in the

past mainly by using a profiler located on the shore and the 7km inland Radio

sonde (00:00, 12:00 GMT). The summer climate is usually governed by the

synoptic Persian Troughs together with the land- sea interaction. In the morning

the fast rate of earth heating creates thermals which inflate the marine inversion

aloft. This process is suppressed when the sea breeze penetrates the shore line,

decreasing the thermal energy, thus resulting in the subsidence of the mixing

layer height. It was shown that the decrease rate is connected to the depth of the

Persian through, and it becomes shallower and also starts at a later hour as the

distance from shore increases. A two years summer study using a Lidar and a

Ceilometer showed good correlation between them PBL height and the aerosol

vertical distribution with time in both instruments. The winter that was less

studied. The current period covers part of 2013 summer and the dry winter of

2014 that were unusual compared to a normal season including some eastern

wind events and very early Sharav phenomena.

The Ceilometer data was analyzed along with the AERONET data from the closest

station, as well as radio sonde data and the information of the Hysplit program

and weather models, in order to try and gain better understanding of the daily

aerosol patterns. Some examples will be shown.

P5.2 Comparison of ACSM measurements with off line and on-line techniques

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I. Stavroulas, A. Bougiatioti, N. Kalivitis, G. Kouvarakis, C. Theodosi, P. Nikolaou

and N. Mihalopoulos

Using a variety of analytical techniques, aerosol chemical and physical properties

have been continuously being monitored at Finokalia, Crete. The main

infrastructure deployed features an Aerosol Chemical Speciation Monitor (ACSM)

which measures organics, sulfate, nitrate, ammonium and chloride at a 30 minute

resolution time. Chemical composition of aerosols is also being monitored via

daily sampling on filters. Organic and Elemental Carbon (OC and EC) are

measured using a SUNSET analyzer, while [SO4-], [NH4+], [NO3-], [Cl-], [K+],

[Mg2+] are determined via Ion Chromatography (IC). Black Carbon mass

concentrations are monitored using a seven wavelength Aethalometer. Number

size distributions of ultrafine particles are recorded using a Scanning Mobility

Particle Sizer (SMPS), while the aerosol scattering coefficient is determined using

Nephelometers operating at both fine and coarse modes.

A comparison between the various techniques offers a valuable insight on the

properties of the Eastern Mediterranean aerosol population, while on the other

hand allows a thorough quality check of ECPL’s instrumentation at Finokalia. The

comparison will be presented, focusing on the time period in which the ACSM is

deployed at Finokalia, i.e from May 2012 to December 2013. The sum of ultrafine

particle mass concentrations measured by the ACSM and Aethalometer, namely

both refractory and non-refractory PM-1 particle mass concentrations, was in

good agreement with mass concentrations derived from the particle number size

distributions. In addition different species mass concentrations were in good

correlation with those acquired from filter analysis. ACSM organics exhibit almost

identical time variation to the OC measured from filters, while the same behavior

is observed when each one of the other ACSM measured species where compared

to ion concentrations from IC. Finally, aerosol surface, derived from the SMPS

measurements, was in accordance with the scattering acquired by the

Nephelometers.

P5.3 Results of a European inter-laboratory comparison study for the quantification

of biomass burning molecular tracers (levoglucosan, galactosan, mannosan) in

atmospheric particulate samples

S. Verlhac, A. Albinet, O. Favez, J.-L. Jaffrezo, Eva Leoz-Garziandia,M. Aurela, J.-L.

Besombes, M. Claeys, B. van Drooge, A. Hoffer, A. Kasper-Giebl, Y. Linuma, W.

Maenhaut, G. Matuschek, A. Piazzalunga, J. Sciare, E. Swietlicki

A European inter-laboratory comparison (ILC) for the analysis of levoglucosan and

its isomers (galactosan and mannosan) was organized within the European

ACTRIS project (WP3). The ILC was led by INERIS with the help of LGGE for quality

control analyses.

Four test materials were sent to the participants including two ambient air filter

samples (corresponding to high winter range concentrations), one laboratory

blank filter and one standard reference material (NIST SRM). The main purpose of

the ILC was to evaluate the analytical repeatability and reproducibility standard

deviations obtained by the participants using their own analytical methods and to

highlight any bias or influencing factor on the measurement quality of the

biomass burning molecular tracers.

Thirteen participants submitted their results and most of them obtained

satisfactory Z scores (Figure 1). Only two laboratories showed outliers for

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levoglucosan, and only one more also showed unsatisfactory results for

mannosan and/or galactosan. One laboratory showed a very high blank value for

levoglucosan. Only 3 laboratories showed standard deviations of repeatability

larger than 10 %. Standard deviations of reproducibility were about 20-25 % for

levoglucosan and mannosan, while values in the range 30-60 % were obtained for

galactosan. All the results obtained showed that the analytical procedure had no

influence on the quantification of levoglucosan and its isomers.

Expanded uncertainties obtained were satisfactory (e.g. < 52 % for levoglucosan)

and, for example, consistent with the one required for the measurement of

benzo[a]pyrene in ambient air PM10 (European Directive 2004/107/CE). Finally,

results of this ILC could be used as reference for the certification of the NIST SRM

1649b (urban dust).

P5.4 A Depolarization Lidar based Method for the Determination of Microphysical

Cloud Properties in Water Clouds near Cloud-Base

D.P.~Donovan, H-K~Baltink

The links between multiple-scattering induced depolarization and cloud

microphysical properties (e.g. cloud particle number density, effective radius,

water content) have long been recognized. Previous efforts to use depolarization

information in a quantitative manner to retrieve cloud microphysical cloud

properties have also been undertaken but with limited scope and, arguably,

success. In this work we present a retrieval procedure applicable to semi-

adiabatic liquid stratus clouds. Limiting the applicability of the procedure to

clouds whose structure resembles that of a semi-adiabatic model around cloud-

base (i.e. constant liquid-water constant (LWC) slope and constant number

density) allows us to reduce the cloud variables to two parameters (namely the

derivative of the LWC with height and the extinction 100 meters above cloud-

base). This simplification, in turn, allows us to employ a fast and robust inversion

procedure based on a look-up-table approach applied to extensive lidar Monte-

Carlo multiple-scattering calculations. In this paper we describe the theory

behind the inversions procedure and discuss its strengths and limitations. Several

validation case studies are presented where the results of the inversion procedure

are compared with simultaneous cloud radar observations. In non-drizzling

conditions it was found that the lidar-only inversion results can be used to predict

the radar reflectivity within the radar calibration uncertainty (2-3 dBz). Results of

a comparison between ground-based aerosol number concentration and lidar-

derived cloud base number considerations are also presented and discussed.

13:00 End of 4th

ACTRIS General Meeting

13:00-14:30 Lunch break

ACTRIS - 2 Writing Group

Friday, 13 June, 14:30 – 18:00

15:30-16:00 Coffee break

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