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NMVOC emissions estimated from HCHO GOME-2 satellite data

Belgian Institute for Space Aeronomy Brussels, Belgium. NMVOC emissions estimated from HCHO GOME-2 satellite data. J-F. Muller, J. Stavrakou I. De Smedt, M. Van Roozendael. GEIA/ACCENT Workshop, Oslo, 26-29 Oct. 2009.

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NMVOC emissions estimated from HCHO GOME-2 satellite data

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  1. Belgian Institute for Space Aeronomy Brussels, Belgium NMVOC emissions estimated from HCHO GOME-2 satellite data J-F. Muller, J. Stavrakou I. De Smedt, M. Van Roozendael GEIA/ACCENT Workshop, Oslo, 26-29 Oct. 2009

  2. Inverse modeling: constrain/improve emission inventories based on atmospheric chemical observations and an atmospheric model Cost function : measure of the discrepancy between the model and the observations J(f)=½Σi (Hi(f)-yi)TE-1(Hi(f)-yi) + ½ (f-fB)TB-1(f-fB) B : error covariance matrix on the control variables y: observations E : observation error covariance matrix fB: 1st guess values of the control variables f : control variables vector H : model operator acting on the control variables • - Choice of control parameters • Emission categories • Spatial resolution of the inversion • Temporal resolution • Results depend on assumed error covariance matrices for observations and control variables

  3. 85% Biogenic Biogenic NMVOCs 30% Biomass burning Anth. 7% 12% 3% Anthropogenic Fires, 3% CH4 oxidation, 60% • Potential of spaceborne HCHO columns to yield quantitative information on NMVOC emissions (Palmer et al., 2003, 2006, Fu et al., 2007, Dufour et al., 2009, Stavrakou et al., 2009) • NMVOCs : short-lived compounds, ozone and SOA precursors • large uncertainties in emissions/speciation Globally ~1200 Tg/year NMVOCs EMISSIONS Global total HCHO ca. 1600 Tg/yr Lifetime = 5 h GLOBAL HCHO BUDGET

  4. IMAGESv2 HCHO columns SCIAMACHY HCHO (BIRA-IASB)‏ 1015molec. cm-2 Inverse modeling:derive updated NMVOC emissions by adjusting the emissions used in the CTM so as to minimize the model/data biases Adjoint technique : powerful tool for non-linear problems with a large number of unknowns  inversions at the model resolution, distinguish between emission categories

  5. Inversion results using SCIAMACHY HCHO data and IMAGES at 5°x5° resolution (Stavrakou et al., 2009) Updated/prior pyrogenic emissions Updated/prior biogenic emissions • strong increase over South Africa • 30% reduction over N. America (consistent with independent evaluation of isoprene emissions based on aircraft data) • 30% decrease over Indonesia • large decrease over the Northern african savanna & over Indonesia, • up to x2 increase over S. Africa • HCHO data clearly provide useful constraints for biogenic NMVOC (isoprene) emissions and biomass burning, BUT

  6. Anthropogenic NMVOC signal in the HCHO columns? • anthropogenic sources are significant over populated/industrialized areas, but their contribution is small (7%) at the global scale • over the US: big cities/anthropogenic signal not clearly identifiedby SCIAMACHY/OMI (Millet et al., 2008) • in constrast, significant enhancement observed over Chinese cities using 6-year averaged GOME data (Fu et al., 2007) • GOME-2/Metop : successor of GOME and SCIAMACHY, launched in October 2006 • global coverage in 1.5 day  higher signal-to-noise ratio

  7. 2008 GOME-2 HCHO IMAGESv2 HCHO (now at 2°x2.5°) January 1015molec.cm-2 July

  8. Anthropogenic Biogenic (isoprene) A priori emissions Correction factors Far East : +50%, Europe: -30%, N.America: -40% patterns roughly similar to inversion results using SCIAMACHY HCHO

  9. Updated/a priori anthropogenic emissions July 2008 • +95% increase over China, +70% over India • China: 27 Tg/yr in 2008, 17.2 Tg/yr in REAS (Ohara et al., 2007) for 2003 • Fu et al. 2007 inversion using GEOS-Chem and 1996-2001 GOME: anthropogenic +25%, biogenic x4, b.burning x9

  10. GOME-2 HCHO column over the Far East July 2008 1015molec.cm-2 Modeled HCHO column using a priori emissions Updated HCHO column

  11. Summary • For biogenic emissions and biomass burning, consistency of the updated emissions with inversions based on SCIAMACHY HCHO • Global isoprene emission = 400 Tg/year • However, strong evidence from field campaigns, theoretical and laboratory studies that the isoprene oxidation mechanism should be revisited (Lelieveld et al. 2008, Peeters et al. 2009, Paulot et al. 2009) • Reduction of anthropogenic VOC emission over Europe, US and Middle East • Factor of 2 increasefor anthropogenic Chineseemissions, +70% in India • However, optimization fails to reproduce high HCHO levels over these regions • More work needed to refine the chemical oxidation scheme to include more explicit anthropogenic precursors of HCHO jfm@aeronomie.be http://tropo.aeronomie.be Thank you for your attention

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