Satellite-Derived Estimates on Methane Emissions From Rice Paddies Across China

On the basis of Tro!pospheric Monitoring Instrument (TROPOMI) XCH4columns, gridded methane (CH4) emissions from rice paddies across China were estimated in this study. The proposed method follows the principle of bottom-up analysis, and the key factor of methane emission rate was estimated from TROPOMI observations. Via the use of 175 data pairs of field-observed methane emission rates across paddy fields in China and the corresponding XCH4enhancements in paddy fields compared with local background areas, a forward model was established, with a R2value of 0.86 (p4enhancement in rice paddies than in local background areas at a 0.5°-resolution ranged from 0.04 to 16.57 ppb across China, and the mean methane emission rate reached 5.10 ± 3.29 mg CH4m-2yr-1, with high spatial variation across eastern China. Considering rice cultivate areas, the rice-growing season, and the estimated methane emission rates, the national methane emission from rice paddies was estimated to reach 5.88 Tg CH4yr-1. The proposed method provides insights into the estimation of methane emissions from nonpoint sources on the basis of satellite observations.