A study of synthetic 13 CH 4 retrievals from TROPOMI and Sentinel 5/UVNS Part 1: non scattering atmosphere

Abstract

Abstract. Retrievals of methane isotopologues have the potential to differentiate between natural and anthropogenic methane sources types, which can provide much needed information about the current global methane budget. We investigate the feasibility of retrieving the second most abundant isotopologue of atmospheric methane (13CH4, roughly 1.1\u2009% of total atmospheric methane) from the Shortwave Infrared (SWIR) channels of the future Sentinel 5/UVNS and current Copernicus Sentinel 5 Precursor TROPOMI instruments. With the intended goal of calculating the δ13C ratio, we assume that a δ13C uncertainty of better than 10\u2009‰ is sufficient to differentiate between source types, which corresponds to a 13CH4 uncertainty of