Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 10 8 2010 10.5194/acpd-10-19031-2010 http://www.atmos-chem-phys-discuss.net/10/19031/2010/ http://www.atmos-chem-phys-discuss.net/10/19031/2010/acpd-10-19031-2010.html http://www.atmos-chem-phys-discuss.net/10/19031/2010/acpd-10-19031-2010.pdf 19031 19069 2010-08-11 GOME-2 observations of oxygenated VOCs: what can we learn from the ratio glyoxal to formaldehyde on a global scale? M. Vrekoussis vrekoussis@iup.physik.uni-bremen.de F. Wittrock A. Richter J. P. Burrows Institute of Environmental Physics and Remote Sensing, IUP, University of Bremen, NW1, P.O. Box 33 04 40, 28334, Bremen, Germany Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK Collocated data sets of glyoxal (CHO.CHO) and formaldehyde (HCHO) were retrieved for the first time from measurements of the Global Ozone Monitoring Experiment-2 (GOME-2 during the first two years of operation in 2007 and 2008. Both oxygenated Volatile Organic Compounds, OVOC are key intermediate species produced during the oxidation of precursor hydrocarbons. Their short lifetime of a few hours in the lower troposphere links them to emission sources and makes them useful tracers of photochemical activity. The global composite maps of GOME-2 HCHO and CHO.CHO have strong similarities confirming their common atmospheric and/or surface sources. The highest column amounts of these OVOCs are recorded over regions with enhance biogenic emissions (e.g. tropical forests) in South America, Africa and Indonesia). Enhanced OVOC values are also present over areas of anthropogenic activity and biomass burning (e.g. over China, N. America, Europe and Australia). The ratio of CHO.CHO to HCHO, <i>R</i>_GF, has been used, for the first time on a global scale, to classify the sources according to biogenic and/or anthropogenic emissions of the precursors; <i>R</i>_GF between 0.040 to 0.060 point to the existence of biogenic emissions with the highest values being observed at the highest Enhanced Vegetation Index, EVI. <i>R</i>_GFs below 0.040 are indicative of anthropogenic emissions and associated with high levels of NO₂. This decreasing tendency of <i>R</i>_GF with increasing NO₂ is also observed when analyzing data for individual large cities, indicating that it is a common feature. The results obtained for <i>R</i>_GF from GOME-2 data are compared with the findings based on regional SCIAMACHY observations showing good agreement. 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