Abstract:
Methane is an important greenhouse gas, and rice cultivation is one of the major anthropogenic sources of methane emissions. Based on the TROPOMI satellite observations ranging from May 2018 to April 2022, this study comprehensively analyzes the methane varying modes in the China using various techniques such as STL decomposition. The seasonal variations of methane concentration in the Chinese region were categorized into four types of modes by seasonal terms, and the interconnections between these modes and rice cultivation patterns were explored in depth. The results showed that the TROPOMI observations confirmed the important influence of rice fields on the seasonal variations of methane content, and the distribution of methane concentration in China generally showed a decreasing trend from the southeast coast to the northwest interior, and an increasing trend year by year over the time period covered by the study, with the growth rate of methane in most of the provinces being above 0.6%. In addition, the study revealed that the four main seasonal modes (single-peak, double-peak, triple-peak, and multi-peak) could consistently correspond to the rice cultivation density and indirectly reflect the regional rice cultivation patterns.