A review of the research on atmospheric water resources over arid and semi-arid regions of East Asia

Based on recent studies of the atmospheric water resources over arid and semi-arid areas in East Asia (ASEA), the progress is reviewed. Many researches have shown that the water vapor content in the atmosphere over the western and eastern parts of ASEA is higher than that over the central ASEA, and the water vapor content above the leeward slope is higher than that in the windward slope. Cloud water resources over the monsoon region and mountainous areas are higher than over basins and deserts. The water vapor content in the lower troposphere over the ASEA has increased significantly, especially in the summer after the mid-1980s. Under the background of global climate change, the cloud water path over the northwestern part of China tends to increase generally with features of "positive in east and negative in west" and "positive in the north and negative in south". The atmospheric circulation, surface temperature and land cover characteristics all impact the air water resources over ASEA through influencing the water vapor transport and evapotranspiration. The changes in air water resources affect local temperature and precipitation by affecting the radiation budget, the cloud cover and the cloud water content produced by the second phase transition. At present, most of the researches mainly focus on the distribution and variation of water vapor content and cloud mean state over the study area. The characteristics of air water resources associated with precipitation are still unclear and need to be studied systematically.