The Methane Total Column Product from TROPOMI Observations of the Copernicus Sentinel-5 Precursor Mission: Recent Results

Abstract

The Tropospheric Monitoring Instrument (TROPOMI) was successfully launched as single payload of ESA's Sentinel-5 Precursor (S5P) mission on October 13th, 2017. The instrument observes Earth reflected radiances from the ultraviolet to the shortwave infrared spectra range with daily global coverage and with a spatial resolution of 7x7 km2. The telluric absorption around 2.3 mum provides information on the total column amount of methane where the operationally data are processed with the RemoTeC full-physics retrieval algorithm, developed by SRON. In this work, we present recent results on the S5P methane product inferred from nearly one year of TROPOMI measurements. We discuss the use of different data bases for molecular absorption cross sections of water vapor and methane including the recent data of ESA's SEOM-Improved Atmospheric Spectroscopy Databases (IAS) project. Moreover, for selected TCCON sites we apply our retrieval algorithm to radiometric measurements of the Fourier Transform Spectrometers at the ground site and compare the results with the TCCON and TROPOMI methane product to better understand differences between the data products. Finally, the comparison of the methane S5P product with the proxy methane product from the Japanese GOSAT satellite complements the study.