Analysis of long-term (2003–2015) spatial-temporal distribution of atmospheric methane in the troposphere over the Qinghai-Xizang Plateau based on AIRS data

This paper has conducted a contrastive study on the AIRS retrieval results and the observational data of methane concentration at Mt. Waliguan atmospheric background station, and has analyzed the distribution characteristics of atmospheric methane concentration over the Qinghai-Xizang Plateau from 2003 to 2015. The results show that the AIRS retrieval data display the same monthly, annual, and seasonal variation trend, as well as segmental variation characteristics. The methane concentration features high in the north and low in the south along with the geographical line of Kunlun Mountains–Tanggula Mountains–Hengduan Mountains, and decreases significantly as the altitude rises, with the highest and the most sensitive variability in the south central region of the Qinghai-Xizang Plateau. From 2003 to 2015, the methane concentration in the Qinghai-Xizang Plateau continued to rise, with the fastest growth in autumn, the slowest in winter, and an annual growth rate of 5.2 nmol mol⁻¹ a⁻¹, while the growth rate from 2013 to 2015 was lower than the global average. The seasonal variation showed a unimodal curve, with the highest value in summer and the lowest value in spring, and with the altitude rising, the seasonal variation was more significant.