Climatic Distribution Features and Trends of Cloud Water Resources over China

Analysis of cloud water path (CWP) data over China available by the International Satellite Cloud Climatology Project (ISCCP) is performed for the period 1984－2004. The climatology, trends, and variability of CWP are examined. The climatological distribution and variation of CWP are dependent on the circulation, especially the monsoon circulation, topography and atmospheric moisture. Influenced by the Asia monsoon, China's CWP exhibits very large seasonal variations. All-China average shows the maximum CWP in June and the minimum CWP in October. Under the influences of the Tibetan Plateau and the westerly flow, the largest CWP is found in winter and early spring in southeastern China. Linear regression analysis is used to characterize seasonal and annual trends in CWP. Increasing trends in CWP are observed over most of China. Northwestern China, especially over the Tibetan Plateau, and the Inner Mongolia show significant increases of CWP. The largest increase in CWP is in winter and the increasing trend is weakest in spring. These increases in CWP are primarily dependent on the enhanced updraft deduced by the variation of circulation, including the weakening of the summer monsoon system. Interannual variation and trends in CWP are closely correlated to the rise of temperature in China, confirming the enhanced hydrological cycle under the background of global warming.