Analysis on the spatial-temporal variations of methane over China using SCIAMACHY data

Methane is an important anthropogenic greenhouse gas contributing to global climate change, and its warming effect is just second to carbon dioxide. Satellite remote sensing technique can obtain large scale distribution of trace gases, and it has been an important tool in the field of atmospheric observation. This paper presents the spatial-temporal variations of methane in China based on the vertical columns of methane measured by the SCIAMACHY sensor on board ENVISAT. The distribution of annual averaged CH4 vertical columns in China during 2003-2005 shows that the spatial gradients of CH4 vertical column look like a three-level ladder, and low terrain areas such as plains and basins tend to have high CH4 level, but the surrounding terrain also matters. The variation curves of monthly average CH4 vertical columns in China during 2003-2005 show that the peak centers of CH4 are found in summers, and the trough centers in winters. The month where the yearly seasonal component has its maximum in CH4 of Northern China is earlier than that of Southern China. Most parts of China have its minimum in winter and spring except Hainan, whose minimum emerges in summer. The Emissions Database for Global Atmospheric Research (EDGAR) showed that during 2003 to 2008 the total emissions of CH4 in China were increasing year by year, which were high consistency with the trend of the average concentration of atmospheric methane in China. It is estimated that the growth of methane concentration was partly caused by the increase of total emissions of CH4.