Claire Sarrat, Joël Noilhan, Pierre Lacarrère, Sylvie Donier et al.

Atmospheric CO2 modeling at the regional

scale:

A bottom – up approach applied to the

CarboEurope Regional Experiment

campaign (CERES)

OUTLINE

I Objectives of CERES and meso scale modeling

II Atmospheric CO2 modeling at the regional scale

with Meso-NH A ‘golden day’ case study: may-27 A ‘lagrangian experiment’ case study : june-

06

III Intercomparisons of atmospheric meso-scale models

Objectives : to establish a regional budget of CO2 : • 10 surface flux sites (energy, water and CO2) on different types of land cover (forest, vineyards, maize, wheat, rapeseed, beans, grassland, bare soil)

• Atmospheric Boundary Layer (ABL) data: RS, aircrafts, radar UHF…

Experiment in Les Landes, S-W of France:

- from may-16 to june-25 2005

- 21 IOP days

Objectives of the CERES campaign (Dolman et al., BAMS, 2006)

I ObjectivesI ObjectivesII Atmospheric CO2 modeling

III Intercomparisons of models

• CO2 concentrations observations in and above the ABL: Biscarosse, La Cape Sud, Marmande + aircrafts: Piper Aztec, Dimona, Sky Arrow

• ‘Flux divergence’ flights

• LAI monitoring

• Surface and soil properties (Ts, soil water content…)

Objectives of the modeling activity

CO2 regional budget using a meteorological meso-scale model

Meso-NH and the CERES data:

- Test the model ability to simulate the strong surface heterogeneities

- Simulate the CO2 transfers at the boundaries: surface – ABL and entrainment at the ABL top

-Simulate the complex interactions of CO2, heat and water surface fluxes within a regional model

- Simulate correctly the concentrations in the PBL as a necessary condition to retrieve the surface fluxes by inverse modeling (see T. Lauvaux presentation)

I ObjectivesI ObjectivesII Atmospheric CO2 modeling

III Intercomparisons of models

ISBA-A-gs

Meso-NHMeso-NH

LE, H, Rn, W,

Ts…

Atmospheric [CO2] Anthropogen

ic

Sea

Meteorological ModelMeteorological Model SurfaceSurface

Lafore et al., 98Noilhan et al. 89 Calvet et al., 98

CO2 Fluxes

Atmospheric CO2 modelingMeso-NH configuration

I ObjectivesII Atmospheric COII Atmospheric CO22 modeling modelingIII Intercomparisons of models

Large domain : France Horizontal resolution: 10 km

Small domain: CERES domain

Horizontal resolution: 2 km

Nesting 2 ways Land use: Ecoclimap (Masson et al., 2003) Initialization and lateral boundaries forcing: ECMWF model Anthropogenic CO2 emissions from Stuttgart Univ. at 10km resolution

900 km 320 km

Altitude (m)

CO2 concentrations (ppm) may-27 9HUTC

Atmospheric CO2 modeling may–27 Sea breeze effects (Sarrat et al., JGR, 2006)

I ObjectivesII Atmospheric COII Atmospheric CO22 modeling modelingIII Intercomparisons of models

S-WS-ES-E

CO2 concentrations (ppm) may-27 14HUTC

FORESTAREA

AGRICUL.AREA

S-ES-W

Win

d di

rect

ion

FORESTAREA

AGRICUL.AREA

CO

2 co

ncen

trat

ions

Atmospheric CO2 modelling may–27 Boundary layer heterogeneity

OCEAN FORESTAREA

AGRICUL.AREA

Simulated vertical cross section of the mixing ratio at 14UTC

Zi = 900m

Zi = 1600m

Forest

Crops

obsmodel

obsmodel

Atmospheric CO2 modelling : may–27 A scheme of main processes

Atmospheric CO2 modelling : june-06Lagrangian experiment

N-W

I ObjectivesII Atmospheric COII Atmospheric CO22 modeling modelingIII Intercomparisons of models

Atmospheric CO2 modelling : june-06Lagrangian experiment : Budget calculation

N-W6 UTC

15 UTC

CO2 turb. fluxCO2 advection

CO2 variation

<CO2>

Conclusion (1) :Atmospheric CO2 modeling with Meso-NH

The CERES database is well adapted to study the CO2 and water budget at the regional scale

The meso-scale dynamical processes such as sea and vegetation breezes have a strong impact on the spatial and temporal variability of CO2 concentrations in the ABL

The atmospheric CO2 budgeting using meso-scale modelling allows to estimate the contribution of advection and turbulent transport processes on the spatio-temporal variation of the regional CO2 concentration

Intercomparison of 5 meteorological models

Participation of 5 models: RAMS from Amsterdam Vrije Univ., RAMS from Alterra, RAMS from CEAM, WRF from MPI, Meso-NH from CNRMExperimental Protocol agreed on: Domain of simulation at 2km resolution Initialization and lateral boundaries forcing for meteorological and surface variables with ECMWF model

Land cover by the Ecoclimap database including 61 surface classes, summer crops/winter cropsCO2 anthropogenic emissions at 10 km

resolution from Stuttgart Univ. 2 golden days of the CERES campaign: may-27 and june-06 2005

I ObjectivesII Atmospheric CO2 modeling

III Intercomparisons of models III Intercomparisons of models

Intercomparison of 5 meteorological models:Surface fluxes

RN

H

LE

SFCO2

Auradé winter cropmay-27

Le Bray forest

RN

H

LE

SFCO2

Auradé winter crop site is well simulated by all the models

Simulations for Le Bray forest site more difficult for all models

Bsimu [.5, 2] CO2 flux overestimated due to too high respiration?

Intercomparison of 5 meteorological models:Atmospheric Boundary Layer

Most of the models simulate the nocturnal stable ABL and humidity accumulation at low level

At 14H large variation for ABL development :-> 800m RAMS-ALTE->1500m WRF-MPI

RS june-06 05H FOREST

Potential temp

RS june-06 14H FOREST

obs

Potential temp

Z (

m)

Z (

m)

night day

Intercomparison of 5 meteorological modelsVertical profiles of CO2 concentrations (may-27)

morning vertical profile

afternoon vertical profile

Crops

ABL height vs CO2 concentrations: the CO2 concentrations decrease when the ABL is developing due to vertical mixing and assimilation the CO2 depletion is higher over the crops area whereas the vertical mixing in lower than over the forest Generally, the models reproduce the observed trend.

Forestzi

CO2 concentrations

zi

CO2 concentrations

Conclusion (2) :Intercomparison of 5 regional meteorological models

5 models have simulated two contrasted days of CERES according a similar model configuration

The surface fluxes are easier to simulate over fully developed crops than over the pine forest. The windy june-06 case is better simulated.

The surface CO2 fluxes on the warm may-27 are poorly simulated by most models.

Large discrepancies are observed in the simulation of the ABL development and potential temperature

The CO2 concentrations simulated in the ABL present a correct evolution between the morning and the afternoon profiles.

Atmospheric CO2 modelling

Conditions of simulation :

Initialisation of CO2 the day before the simulated day at 18HUTC with a homogeneous vertical profile over the domain of simulations

Meteorological and surface moisture initialisation, lateral boundaries forcing : ECMWF analyses

CO2 anthropogenic emissions from Stuttgart Univ. at 10 km

Land use : Ecoclimap (Masson, 2003, Champeaux et al., 2005)

62 classes of vegetation: Ecoclimap processed from CORINE 2000 and

Vegetation NDVI. Anthropogenic emissions

interpolated at 2km

june-06

Sensitivity to initial conditions

Intercomparison of 5 meteorological modelsVertical profiles of CO2 concentrations

Intercomparison of 5 meteorological modelsAircraft fluxes

CropsForest

The observed aircraft fluxes over forest and crops present large horizontal variations

For MNH-CNRM and RAMS-ALTE CO2 fluxes look consistents

For MNH-CNRM the LE fluxes are overestimated over crops because of an overestimation of the LAI

June-06, 9-11UTC

BOWEN RATIO FOR CROP

OBS 1 .7

MNH-CNRM 1.5 .7

RAMS-AMVU .8 .7

RAMS-ALTE 1.7 1.3

RAMS-CEAM 2.3 1