TROPOMI, the solar backscatter satellite instrument for air quality and climate, heads towards detailed design

The Tropospheric Monitoring Instrument (TROPOMI) is currently planned for launch on ESA's Sentinel 5 precursor satellite in the time frame of 2014. TROPOMI is an ultraviolet-to-SWIR wavelengths imaging spectrograph that uses two-dimensional detectors to register both the spectrum and the swath perpendicular to the flight direction. The swath is about 110 degrees wide to allow daily global coverage from the polar orbit of the Sentinel 5 precursor satellite. The instrument follows the heritage of SCIAMACHY (ENVISAT, launch 2002) and OMI (AURA, launch 2004), but it has been improved in several ways: the ground resolution is down to 7 x 7 km2, the instrument is fit for low albedo scenes and the wavelength bands are optimized using the SCIAMACHY and OMI heritages to have the best trace gas products. The first two improvements basically mean that the instrument aperture is much larger for TROPOMI and, related to this, the reading of the detectors much faster. The selected wavelength bands for TROPOMI are UV1 (270-310 nm), UV2 (310 - 370 nm), VIS (370 - 500 nm), NIR (675 - 775 nm) and SWIR (2305 - 2385 nm). The first three bands are very similar to the OMI bands, the NIR has been added to improve on clouds and air mass corrections and the SWIR allows measuring CH4 and CO. The paper discusses the development status on several topics, such as detector selection and polarization scrambler performance simulations using the TIDE grid based level 2 scene simulator. © 2009 SPIE.