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

On the basis of Tro!pospheric Monitoring Instrument (TROPOMI) XCH₄ columns, 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 XCH₄ enhancements in paddy fields compared with local background areas, a forward model was established, with a R² value of 0.86 (p < 0.01). In 2019, the XCH₄ enhancement 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 CH₄ m^-2 yr^-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 CH₄ yr^-1. The proposed method provides insights into the estimation of methane emissions from nonpoint sources on the basis of satellite observations.