Trends in moisture content for 1979-2010 in China river basins

In order to understand the current status of atmospheric moisture content and to analyze the spatial and temporal variations in the distribution of precipitable water over China, the Japan Meteorological Agency reanalysis data set is used to map distributions of annual and seasonal moisture content for 1979-2010. The obtained maps are compared to those based on sounding data, and necessary corrections to the maps are made accordingly. The study uses China river basins as units for the trend analysis of moisture content. The result shows that there is a little interannual variation in the annual moisture content in each of the China river basins, as revealed by small values of the coefficient of variation (C_V<0.1) for each basin separately. The higher values of C_V>0.06 are found in river basins of Northwest China. Significant upward trends in annual precipitable water have been detected in river basins of Beijiang, Tarim, Hexizoulang and Alashan, Qaidam and Changtang. The opposite is true for river basins of Southeast and Inner Mongolia. No significant trend in moisture content has been found in the rest of China river basins.