Spatial and Temporal Variability of Daily Precipitation Concentration in China during 1960-2011

Based on daily precipitation data during 1960 and 2011, the precipitation concentration index (CI) is calculated for the purpose to study the spatial and temporal variability of daily precipitation concentration in China. The results are as follows. CI can well reflect the degree of precipitation concentration over China. The value of CI is between 0.575 and 0.750, and its mean value is 0.652. The CI values are large in eastern China and in the summer, and small in western China and in the winter. 44.17% of the stations show an upward trend of CI change and 55.83% show a trend of CI decrease, but the trends of CI change at only 10.36% of these stations are significant at the 95% confidence level. Those stations with significant CI increases are mainly distributed over northwestern China, central China, and southwestern China, while those stations with significant CI decreases are mainly distributed over northeastern China, northern China, southeastern coastal areas of China and the eastern Tibetan Plateau. The dominant period of CI change is 3 to 5 years, which is the same as that of precipitation. Significant periodic changes in CI are concentrated within the period from 1970 to 2000.