Temporal and spatial variability of glyoxal as observed from space M. Vrekoussis1, F. Wittrock1, A. Richter1, and J. P. Burrows1,2 1Institute of Environmental Physics and Remote Sensing, IUP, University of Bremen, NW1, P.O. Box 33 04 40, 28334 Bremen, Germany 2Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxfordshire, OX10 8BB, UK
Abstract. Glyoxal, CHO.CHO, is produced during the oxidation of volatile organic
compounds, VOC, released by anthropogenic activities, biogenic processes and
biomass burning. It has a short chemical lifetime of a few hours in the
boundary layer and lower troposphere and therefore serves as an indicator
and a marker of photochemical hot-spots and their response to changing
atmospheric conditions around the globe. For this reason more than five
years of CHO.CHO observations (2002–2007), retrieved from the radiances
measured by the satellite instrument SCIAMACHY, were obtained and analyzed
both temporally and spatially. The largest columns of CHO.CHO
(>6.1014 molec cm−2) are found in the tropical and sub-tropical
regions, associated with high biological activity and the plumes from
vegetation fires. The majority of the identified hot spots are characterized
by a well-defined seasonality: the highest values being observed during the
warm and dry periods as a result of the enhanced biogenic, primarily
isoprene, emissions and/or biomass burning from natural or man-made fires.
The regions influenced by anthropogenic pollution also encounter enhanced
amounts of glyoxal. The ratio "CHO.CHO to HCHO, RGF" over the
biogenically influenced photochemical hot-spots is approximately 0.045. For
the studied regions, the presence of pyrogenic and anthropogenic emissions
increases and decreases this number respectively. Although the 2002–2007
period of observation is limited, over the northeastern Asia a significant
annual increase in CHO.CHO in addition to a seasonal cycle is reported.
Citation: Vrekoussis, M., Wittrock, F., Richter, A., and Burrows, J. P.: Temporal and spatial variability of glyoxal as observed from space, Atmos. Chem. Phys., 9, 4485-4504, doi:10.5194/acp-9-4485-2009, 2009.