TROPOMI Methane (CH4)
Methane (CH4) is the most important greenhouse gas after carbon dioxide (CO2). Approximately three-quarters of methane emissions are anthropogenic. TROPOMI provides CH4 column concentrations with high sensitivity to Earth's surface, spatiotemporal coverage, and accuracy for inverse modeling of sources and sinks. The Sentinel-5 Precursor mission coordinates with S-NPP in order to use VIIRS cloud information for selecting cloud-free TROPOMI pixels. The algorithm baseline describes retrieving the column average dry air mixing ratio of methane (XCH4) from Sentinel-5 Precursor measurements. The dataset offers offline high-resolution imagery of methane concentrations. TROPOMI utilizes absorption information from the Oxygen-A Band (760nm) and the SWIR spectral range to retrieve CH4 abundances. Known data quality issues include incomplete removal of bad pixels, erroneous CH4 values in single TROPOMI overpasses, and unfiltered pixels above inland water. Uncertainties for XCH4 are based on single sounding precision, and for an overall estimate, a proposed error multiplication factor of 2 is suggested.