Sylvia Generoso, Isabelle Bey

Evaluation of aerosol and CO distributions from boreal fires in GEOS-Chem using satellite products

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Preliminary results using the CALIPSO products

LMCA ,École Polytechnique Fédérale de Lausanne, Switzerland

Matthieu Labonne, François-Marie Bréon

LSCE / IPSL, CEA - CNRS, Gif-sur-Yvette, France

Contact: sylvia.generoso@epfl.ch

Jean-Luc Attié

LA, Toulouse, France

Model and satellite observations used

GEOS-Chem version v07-02-03

- resolution 2°x2.5°, 30 vertical levels, 50 tracers, GEOS-4 meteorological fields

- biomass burning emissions for 2003 : interannual and seasonal variations based on AATSR fire counts [Generoso et al, 2003]

- AOT of the fine mode (AOT_fine) including carbonaceous aerosols, sulfates and sea salt

- CO columns applying MOPITT averaging kernel

Aerosol satellite products

- POLDER AOT_{fine_865} (r<0.5 µm)

Polarization and Directionality of the Earth Reflectance aboard ADEOS

Data in 1996/1997, 2003

PARASOL (similar sensor) currently flying on PARASOL (A train)

- MODIS AOT_{fine_550} (r<0.5 µm)

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CO satellite products

- MOPITT

Spring and summer 2003 in Russia

POLDER

MODIS

MOPITT

(May-June-July-August 2003 seasonal mean)

R : 0.65

B:-10±66%

R : 0.72

B:-29±61%

R : 0.78

B:-9±9%

Simulations conducted

Russian fire sources

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Biomass Burning Emission

Injection Height (EIH)

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Deposition processes

Results show :

• aerosol distributions : highly sensitive to daily resolution of BB emission inventories and to injection above the PBL in the late fire season (July and August)
• CO distributions : sensitive to injection above the PBL in the late fire season (July and August)
• Biomass Burning source strenght : underestimate of our emissions in May 2003

Standard simulation:

from July 2002, and analyzed from May to August 2003

Sensitivity simulations:

from April 2003, and analyzed from May to August 2003

Set-up for the “Best Estimate” (BE) simulation

Fire emissions are

1. increased by a factor 3 in May
2. prescribed on a daily-basis
3. Injected up to 4.5 km in July and August

Daily results averaged over the North Pacific

Contribution of the 2003 Russian fires to the Northern Hemisphere

AOT

BC deposition

Ratio between the Best Estimate (BE) and a simulation with the Russian fire sources turned off (woBB)

Contribution of the 2003 Russian fires to the “Arctic Haze” events

Number of days (during MJJA 03) for which the AOT₅₅₀> 0.094 = threshold to define Arctic haze events [Herber et al, J. Geophys. Res., 2002]

Contribution of the 2003 Russian fires to the AOT during the days of Arctic Haze events

Ratio between the Best Estimate (BE) and the standard (STD) simulations

AOT

BC deposition

Preliminary evaluation of the aerosol vertical distribution in GEOS-Chem using CALIPSO lidar products

The CALIPSO mission

Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation

Quick overview

In this study

We use CALIOP attenuated backscatter at 550 nm (Level 1 products)

- CALIPSO is a joint U.S. (NASA) and French (Centre National d’Etudes Spatiales/CNES) satellite mission with an expected 3 years lifetime.

- Launched on April 28, 2006 aboard CloudSat satellite

- Data available since mid-June 2006

- Part of the A-train constellation

- Includes 3 instruments, which measure aerosol and cloud properties :

Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP)

Imaging Infrared Radiometer (IIR)

Wide Field Camera (WFC)

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CALIOP measures attenuated backscatter :

- giving information on the vertical structure of the atmosphere

- including information from aerosols and clouds

- depending on the extinction and the phase function

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CALIOP

GEOS-Chem

July 1, 2006

CALIOP

GEOS-Chem

July 2, 2006

CALIOP

GEOS-Chem

July 3, 2006

CALIOP

GEOS-Chem

July 4, 2006

CALIOP

GEOS-Chem

July 5, 2006

CALIOP

GEOS-Chem

July 6, 2006

Conclusions

- In the standard configuration, the model significantly underestimates the MOPITT CO columns, POLDER and MODIS AOT over the north Pacific during May to August 2003.

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- Increasing the amount of the biomass burning emissions does not necessarily result in significant improvements (except in May).

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- In contrast, the use of daily biomass burning emission inventories improved significantly the aerosol simulations, without any significant effect on the CO columns.

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• The injection of particles up to 4.5 km also impacts our simulation but only in the late fire season (July and August).

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- According to our improved simulation, the 2003 Russian fires contribute to 16-33% to the monthly mean AOT averaged north of 75°N and to 40-56% to the mass of BC deposited. They contribute to more than 30% of the AOT during the days of Arctic haze events in spring and summer.

- Very encouraging preliminary results from the comparisons between GEOS-Chem and CALIOP data !

Additional slides

Surface CO simulated by the BE compared to measurements (CMDL)

ppbv

Injection Mode

David Lavoué, personnal communication

A summary of the sensitive analysis

Contribution of dust to the AOT in the “NPac” window

Monthly versus daily ATSR-derived biomass burning emission inventories

ATSR fire count and emission inventories

ATSR fire counts for 2000

Available from July 96 to Oct 06

The seasonal cycle, inter-annual variations and spatial distributions are based on satellite observations

Definition of “homogeneous” regions

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 An emission constant computed as the ratio between :

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1/ an initial emission estimate (climatology)

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2/ATSR fire count averaged over the region and a long observation period (1999-2004)

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 The emission constant is applied to the monthly ATSR fire count

Generoso et al, ACP, 2003

ATSR versus other satellite products

Although all products do have uncertainties, the ATSR night time restriction does not appear to be significant and show a seasonal cycle that is consistent with the other proxies.

Generoso et al, ACP, 2003

ATSR

AVHRR

TRMM

GLOBSCAR

GBA2000

POLDER-1 : Nov 96 to Jun 97

POLDER-2 : Apr 03 to Oct 03

Total AOT

(Aerosol Optical Thickness)

(over ocean only)

Fine mode AOT

(over ocean and land)

(aboard ADEOS)

Retrieved from polarized light

Retrieved from reflectance

May2003

(local over pass time ~ 10:30 am)