Estimating ground-level CH4 concentrations inferred from Sentinel-5P

Abstract

ABSTRACT Methane (CH4) is an important greenhouse gas; however, there is a lack of large-scale studies on ground-level CH4 concentrations. We estimated global ground-level CH4 concentrations based on the CH4 columns from the Copernicus Sentinel-5 precursor satellite (S5P) and vertical profiles of CH4 concentrations simulated from the Atmospheric Chemical Transport Model (GEOS-Chem). The proposed approach had achieved a high predictive accuracy for monthly ground-level CH4 concentrations, with a correlation coefficient of 0.93 (p < 0.01) and RMSE of 29.93 ppb between the estimated CH4 concentrations and those of ground measurements from the World Data Centre for Greenhouse Gases (WDCGG). Compared with the S5P CH4 columns, the estimated ground-level CH4 concentration has a close spatial relationship with emissions. The high CH4 concentrations occurred in eastern China, northern India, western Russia, eastern U.S., and central Europe. Furthermore, the estimated ground-level CH4 concentrations could reflect the seasonal variations of the observations, with correlation coefficients from 0.14 to 0.92. Our findings highlight the importance of satellite observations on atmospheric CH4 in understanding the spatial and temporal emissions.