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Sulfur dioxide retrievals from OMI

Red Sea shipping emissions
Figure 1: The new algorithm improves the detection of weak SO2 sources.
Click image to enlarge.

In preparation of the upcoming TROPOMI/Sentinel-5 Precursor mission, we have developed a new retrieval algorithm for SO2 vertical columns and applied this scheme to 10 years of observations by the OMI/Aura instrument. In Theys et al. (2015) we compare the SO2 column results with other well established SO2 products from the OMI and IASI sensors, as well as with correlative ground-based multi-axis DOAS measurements performed in Xianghe (China). We show that, in comparison with past data products, our algorithm provides improved performance in capturing weak SO2 sources. This is in particular demonstrated by the first detection of shipping SO2 emissions in long-term averaged OMI data.

Figure 2: Slant column enhancements due to shipping emissions over Gibraltar and the Red sea. OMI SO2 and tropospheric NO data are averaged for 2005-2009 to obtain shipping lanes spatial cross-sections.
Red Sea shipping emissions
Figure 3: Long-term averaged OMI data show SO2 ship emissions over the Red Sea, despite strong contamination by land sources. Colour coded vertical columns are in Dobson Units [DU] (1 DU =2.69 x 1016 molecules cm-2).

Online article:

Please cite this article as: Theys, N. et al. (2015), Sulfur dioxide vertical column DOAS retrievals from the Ozone Monitoring Instrument: Global observations and comparison to groundā€based and satellite data, J. Geophys. Res. Atmos., 119, doi:10.1002/2014JD022657.


N. Theys (
Last update on 25 Feb 2015