TEMIS User Workshop, Frascati, Italy

October 8-9, 2007

Formaldehyde application

Derivation of updated pyrogenic and biogenic

hydrocarbon emissions over the last decade

Jenny Stavrakou

Belgian Institute for Space Aeronomy, Brussels, Belgium

Outline

HCHO chemistry, sources and sinks

NMVOCs - Current emission inventories

Impact of NMVOCs on O3 and HCHO

Model, data and inversion method

Simulated against observed HCHO columns

Inversion results over South East Asia and Africa

Objective :

Use HCHO columns in order to assess the performance of current biomass burning and biogenic emission inventories

HCHO chemistry, sources and sinks

CH4

OH

HCHO

HO2

CH3O2

NMVOC

RO2

CH3OOHOH OH

NO

OH

CO+2HO2

CO+H2

CO+HO2+H2O

deposition

The most abundant carbonyl in the atmosphere

Short-lived - lifetime on the order of a few hours

Directly emitted from fossil fuel combustion and biomass burning

Also formed as a high-yield secondary product in the CH4, and NMVOC oxidation

Involvement in tropospheric photochemistry

NMVOCs

Non-methane hydrocarbons

Oxygenated non-methane hydrocarbons

Short-lived species

Production of organic aerosols

Impact of NMVOCs on O3 mixing ratios

July 1997

Simulations performed with the IMAGES global CTM

without NMVOCs with NMVOCs

Impact of NMVOCs on HCHO mixing ratios

July 1997

without NMVOCs with NMVOCs

Emission categories

Global total

(Tg C /yr)Reference

Biogenic 1150 Guenther et al. 1995

Anthropo-genic 160 EDGAR

Biomass burning 40

Lobert et al., 1999

Andreae, 2007

C5H843%

C10H1611%

ORVOC23%

OVOC23%

85%

12%3%

Biogenic

Anthropogenic

Biomassburning

NMVOC global burdens difficult to derive

large uncertainties in the speciation

key uncertainties in global modelling of highly reactive gases

serious discrepancies between inventories

Potential of spaceborne HCHO columns to provide quantitative information about biomass burning and biogenic NMVOC emissions

What is the total HCHO modelled column composed of?

CH4 oxidation Anthrop. sources958 Tg 109 Tg

472 Tg48 TgBiomass burning Biogenic

2006 Annual Mean

CTM with a chemical scheme optimized with respect to HCHO production, i.e. comprising a large number of explicit NMVOCs emitted by fires and vegetation

Bottom-up inventories

HCHO columns

An inversion method necessary to « bring back » the observed HCHO columns to top-down NMVOC emissions

IMAGES global CTM, res. 5x5x40, driven by monthly mean ECMWF fields (Muller and Stavrakou, 2005), updated chemical scheme (Stavrakou et al., 2007)

GFEDv1 and 2 (van der Werf et al., 2003,2004,2006), MEGAN-based database (Guenther et al., 2006, Muller et al., 2007)

TEMIS dataset over 1997-2006

Adjoint model of IMAGES (Stavrakou and Muller, 2006, Stavrakou et al., 2007)

Optimize the fluxes emitted from every model grid cell and month between 1997 and 2006

Distinguish between biomass burning, and biogenic sources

SE Asia

Dashed lines : prior

solid lines : posterior

GFEDv1

GFEDv2

- - - - - : prior, : posterior GFEDv1 GFEDv2

• ~35% decrease in the posterior GFEDv2 inversion

• very good match after optimization

Africa

Dashed lines : prior

solid lines : posterior

GFEDv1

GFEDv2

What’s next?

Objectives:

first assessment of the performance of the current inventories / construction of top-down inventory for pyrogenic/biogenic NMVOC emissions over the last decade

optimization of the IMAGES chemical scheme to account for HCHO production from anthropogenic NMVOCs

provide updated estimates for anthropogenic NMVOCs using inversion

Move towards a finer model resolution (e.g. 2Ox2.5O)

Need for long consistent data series

Plan to use HCHO columns from GOME2 (higher resolution)

References:

1) Stavrakou et 2) Stavrakou et al., Evaluating the performance of pyrogenic and biogenic emission inventories against one decade of space-based formaldehyde columns, in prep.

3) Muller et al., Global isoprene emissions estimated using MEGAN, ECMWF analyss and a detailed canopy environment model

4) Stavrakou and Muller, Grid-based versus big region approach for inverting CO emissions using Measurement of Pollution in the Troposphere (MOPITT) data, JGR, 2006

5) Muller and Stavrakou, Inversion of CO and NOx emissions using the adjoint of the IMAGES model, ACP, 2005