Sulfur dioxide retrievals from TROPOMI : algorithmic developments, verification on synthetic spectra and application to OMI measurements

The TROPOspheric Monitoring Instrument (TROPOMI) will be launched in 2016 onboard the ESA Sentinel-5Precursor (S-5P) platform an d will provide global observations of atmospheric trace gases, with unprecedented spatial resolution. Sulfur dioxide (SO2) is a key atmospheric constituent and measurements from TROPOMI will improve the monitoring capability of SO2 from anthropogenic and volcanic emissions, and will extend the long-term datasets from past and existing UV sensors (TOMS, GOME, SCIAMACHY, OMI, GOME-2, OMPS). In this presentation, we give an overview on the work done on SO2 retrievals as part of the S-5P level-2 processor development. Within the S-5P project, BIRA-IASB is in charge of the development of the prototype algorithm for the retrieval of SO2, while MPIC and DLR are responsible for the verification algorithms, developed in parallel to test and challenge the prototype algorithm. We will describe the different algorithms, their main features and discuss the results of the inter-comparison of the SO2 algorithms applied to synthetic and measured (OMI) spectra. We will also show results of the prototype algorithm applied to OMI with a focus on anthropogenic SO2, for strongly polluted regions (including validation results in China) and weak sources (only detectable in long-term averaged data).