A long-term tropospheric SO2 record from GOME and SCIAMACHY
Andreas Richter(1), Folkard Wittrock(1) and John P. Burrows(1)
(1) University of Bremen, Otto-Hahn-Allee 1, 28259 Bremen, Germany
Satellite observations performed using UV/visible absorption spectroscopy on scattered sun-light provide a unique dataset on global tropospheric composition. While the number of observable species in this wavelength region is limited, it includes key species such as O3, NO2, HCHO, halogen oxides and also sulphur dioxide, SO2.
Sulphur dioxide is mainly emitted from anthropogenic activities although volcanic emissions can be significant locally, in particular in case of large eruptions. Sources of SO2 are the combustion of sulphur rich coal, oil and gas handling and smelting of ores. As a result of improvements in filter technology and also the change to cleaner fuels, SO2 emissions are decreasing in many industrialised countries. At the same time, emissions in Asia have been increasing over the last decade as the economies have been developing and energy needs have increased.
In the atmosphere, SO2 is relevant for its impact on human health, the aquatic biosphere and also its ability to form aerosols. The latter are of large importance for the man made greenhouse effect, and the details of the aerosol effect on global warming are still a topic of discussion.
In this presentation, data from the GOME and SCIAMACHY instruments are analysed for tropospheric SO2 columns using the Differential optical Absorption Spectroscopy (DOAS) method. The focus is on pollution signals over the US and China and their temporal evolution. As SO2 retrievals have relatively large uncertainties, sensitivity studies were performed to evaluate the dependence of the results on a priori assumptions and retrieval settings. The data are also compared to recent results from the GOME-2 instrument on MetOp A.