SO2 from GOME measurements
Sulphur Dioxide (SO2) is released to the troposphere mainly by fossil fuel combustion, volcanic emissions and oxidation of organic material in soils as well as biogenic emissions over the oceans (DMS, H2S).
In the GOME spectra, the characteristic absorption structures of SO2 are readily identified in the spectral range of 315 to 327 nm, and using the Differential Optical Absorption Spectroscopy (DOAS) algorithm, integrated columns of SO2 can be determined. The challenge in quantifying the tropospheric SO2 is related to the fact, that as a result of the increased scattering in the UV, the sensitivity to the lowermost troposphere is strongly reduced compared to the upper troposphere. In order to account for this effect, an a priori assumption has to be made on the shape of the vertical distribution of SO2, which has a significant impact on the final result.
While the global background concentration of SO2 is difficult to quantify with GOME measurements, volcanic eruptions can readily be observed, and the emission plumes be monitored over several days. This also holds for minor explosions and continuous outgasing, that are difficult to monitor from the ground.
Under favourable conditions (no clouds, strong inversion), much smaller but still significantly enhanced SO2 columns can be observed in regions with intense coal burning, in particular in winter. The detection of anthropogenic SO2 emissions from space is another demonstration of the up to now unparalleled sensitivity of the GOME instrument towards tropospheric constituents.
Total columns of SO2 based on GOME Near Real Time data can be found on the GOME NRT page.
Plots of measurements taken during eruptions of Mount Etna, Italy in autumn 2002 and summer 2001 can be found in the tables below. This analysis is based on GOME Near Real Time data (courtesy of ESA/ESRIN/DLR), and values may change in the final analysis. See also the SCIAMACHY First Results page for SCIAMACHYs view of the eruption.
Autumn 2002 eruption:
Summer 2001 eruption:
If you are interested in more information or GOME SO2 data, please contact Andreas Richter.