Spatial and temporal variability of precipitation over China, 1951-2005

Annual, winter and summer precipitation records for the period 1951-2005 from 160 stations in China were analysed using the rotated empirical orthogonal function (REOF), the Mann-Kendall trend test and the Continuous Wavelet Transform (CTW) method. The REOF method was used to analyse the annual and seasonal variability of precipitation patterns over China, the Mann-Kendall method was used to detect the temporal trend of the rotated principal components time series, and the continuous wavelet method was used to explore the periodicity of precipitation changes. In general, six coherent regions across China are identified using the REOF method: north-east China; the middle and lower Yangtze River basin; the Haihe River and the Liaohe River; north-west China; the middle Yellow River and the South-east Rivers (rivers in south-east China). Continuous wavelet transform results indicate that the significant 2-4 year and 6-9 year bands are the major period components. Precipitation in China is uneven in space and time, and its complex temporal structure and spatial variations are different in each season. The Mann-Kendall test results show that, in general, the middle and the lower sections of the Yangtze River are dominated by increasing annual, summer and winter precipitation. Increasing annual precipitation can be observed in north-west China. Increasing summer precipitation is found in north-east China and the Pearl River basin, and the South-east Rivers are dominated by increasing winter precipitation. The availability of water as a resource is in close association with precipitation changes; therefore, this research will be helpful to watershed-based water resource managers in China.