Temporal and spatial heterogeneous distribution of tropospheric CO2 over China and its possible genesis
Increase of greenhouse gas generated by human activities is one of the primary causes for global warming. Mid-troposphere CO2 data retrieved by AIRS (atmospheric infrared sounder), which had been running for 13 years, were validated with ground-based stations observations in this study. Then the spatial and temporal distribution and seasonal variations of CO2 concentration in China were studied with a variety of related data. The results show that there was a high CO2 concentration zone between 30 to 60 over the northern hemisphere, and a low concentration center over low latitudes from 15 degrees S to 15 degrees N, 140 degrees W eastward to 100 degrees E. AIRS CO2 products show good agreement with ground observations, with a 1.926 ppmv . a(-1) annual growth rate. Concentration of mid-troposphere CO2 was higher over northern China than over southern China, and there were four centers of high concentration located in the southwest of Northeast China, west Inner Mongolia, east and west Xinjiang, and low concentrations over Yunnan and the Tibetan area. There existed a significant seasonal CO2 variation with peak in spring, followed by winter and summer, and the lowest concentration occurs in autumn. The seasonal evolution of CO2 is closely related to the transport of the wind field, removal of precipitation and absorption of vegetation.