Abstract: Water resources dispute has become as one of the highlight factors that threaten the national security in Central Asia. As an important component of global water cycle, the distribution and variation of water vapor in upper tropospheric is significative for water resources allocation in Central Asia. This paper discusses the spatiotemporal variation and anomaly of water vapor in upper troposphere over Central Asia during the period of 2003-2011 based on water vapor mass mixing ratio data from the Atmospheric Infrared Sounder (AIRS) satellite instrument, and the obvious differences between Central Asia and the Asian monsoon region (such as the Qinghai-Tibetan Plateau) and tropical monsoon area were revealed. The results revealed that water vapor in upper troposphere over the lowand midlatitude regions in Central Asia maintained a low value, and the monthly variation was relatively stable. Compared with the high water vapor concentration over the south Qinghai-Tibetan Plateau and the northern tropical monsoon area, the Central Asia from the Black Sea-Caspian Sea to west Xinjiang was detected as an area with low water vapor concentration. Water vapor in upper troposphere over Central Asia was slightly increased with a remarkable fluctuation in recent 9 years. The minimum and maximum values of water vapor occurred in 2009 and 2010 respectively, and this significant fluctuation between these two years affected significantly the linear trend of water vapor during the period of 2003-2011. Seasonally, the water vapor concentration was in a slight decrease trend in spring, a slight increase trend in summer, a significant increase trend in autumn, and there was a significant 2-3year fluctuation in winter.

Key words: water vapor in upper troposphere, AIRS, water resources, Qinghai-Tibetan Plateau, tropical monsoon area, Central Asia