Accent-troposat 2 final workshop, 30 Sept. - 01 Oct. 2008, FMI Helsinki, Finland

Atmospheric bromine monoxide retrieval from space and ground-based

UV-visible observations

Nicolas Theys, F. Hendrick, M. Van Roozendael

Belgian Institute for Space Aeronomy (IASB-BIRA)

Brussels

Troposat-2

Acknowledgements to:

BIRA-IASB Univ. of Bremen

- I. De Smedt - A. Rozanov & colleagues

- Q. Errera, S. Chabrillat, F. Daerden

- B. Dils

Univ. of Heidelberg NIWA

- M. Dorf - P. Johnston

- K. Pfeilsticker - K. Kreher

Univ. of Cambridge

- X. Yang

Scientific activites within the AT-2 project (TG1)

1. Development of techniques to retrieve BrO columns and profiles

from ground-based observations:

- Harestua (60°N,11°E)

- Observatoire de Haute-Provence (OHP; 44°N, 6°E)

- Reunion Island (21°S, 55°E)

- Lauder (45°S, 170°E)

2. Satellite total BrO columns retrieval : scientific products - GOME

- SCIAMACHY- (+GOME-2)

3. Retrieval of tropospheric BrO columns: GOME, (+GOME-2).

4. Modelisation of stratospheric BrO using BASCOE.

5. Comparison between satellites, ground-based, balloon and modelled

BrO data sets.

Overview

1. Multi-year comparison of stratospheric BrO retrieved from

SCIAMACHY limb and GB observations

2. Long-term trend of stratospheric BrO using GB observations

3. Development of a stratospheric BrO climatology using the BASCOE

model – application to the retrieval of tropospheric BrO VCD from

GOME-2 (preliminary results)

4. Volcanic BrO observed by GOME-2 during the Kasatochi eruption

Comparison of strato. BrO retrieved from SCIAMACHY limb and GB observations

Harestua 60°N

OHP 44°N

Lauder 45°S

Hendrick et al., submitted to ACPD

SCIAMACHY limb stratospheric BrO profiles retrieved at the IUP/ Univ. of Bremen (scientific product version 3.2)

15-27 km BrO partial columns (altitude with high sensitivity to BrO profile for both instruments)

Reasonable agreement:

relative difference < 11%

standard deviat. in the 13-19% range

A small seasonal dependence in the relative difference between both data sets is observed

Long-term trend of stratospheric BrO using GB observations

Hendrick et al., GRL, 2008

Trend analysis including linear and seasonal components (polyharmonic functions).

Trend values at both stations agree whithin their combined error bars.

Indication that Montreal Protocol restrictions on brominated substances have now reached the stratosphere.

Development of a stratospheric BrO climatology using the BASCOE model

Motivation: retrieval of tropospheric BrO columns from satellite nadir observations (GOME, SCIAMACHY, GOME-2) → need to correct for the BrO absorption in the stratosphere

the impact of the atmospheric dynamics and the photochemistry on the stratospheric BrO distribution is accounted for by making use of O3 and stratospheric NO2 columns simultaneously measured by the satellite instrument.

the parameterization is based on the BACOE 3D-CTM which has been fully optimized for bromine chemistry and budget, and validated through comparisons using ground-based, balloon and SCIAMACHY limb observations.

12-20 km BrO partial columns 15-30 km BrO partial columns (zonal mean)

Theys et al.,

ACPD, 2008

Application to the retrieval of tropospheric BrO VCD from GOME-2

preliminary results

Tropospheric VCD

Total VCD

Stratospheric VCD

September 2007 (sza<80° & CF<0.4)

Tropospheric AMFs are calculated using BrO profiles from the pTOMCAT model

Volcanic BrO observed by GOME-2

Kasatochi volcano (Alaska, 52.17°N, 175.51°W) massive eruption of 7th August 2008

Initial condition: 1 kg of BrO in 10-12 km height layer

- Strong indication of the direct injection of at least 25-35 tons of

reactive bromine in the UT/LS!

- Transport north-eastward by fast near-tropopause jet-winds

paper in preparation - submission soon in GRL

- Strong indication of the direct injection of at least 25-35 tons of

reactive bromine in the UT/LS!

- Transport north-eastward by fast near-tropopause jet-winds

paper in preparation - submission soon in GRL