Spatial and temporal variability of annual and seasonal precipitation over the desert region of China during 1951-2005

The spatial and temporal variations of precipitation in the desert region of China (DRC) from 1951 to 2005 were investigated using a rotated empirical orthogonal function (REOF), the precipitation concentration index (PCI) and the Mann-Kendall trend test method (M-K method). In addition, the association between variation patterns of precipitation and large-scale circulation were also explored using the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis data. The results indicated that the spatial pattern of precipitation was primarily the local climate effect significant type, with the first three EOFs explaining a total of 55.3% of the variance, and the large-scale climate system effect type, which explained 9.8% of the variance. Prior to the 1970s, the East Asian summer monsoon was stronger, which resulted in abundant precipitation in the Inner Mongolia region. Conversely, the climate of the Xinjiang region was controlled by westerly circulation and had lower precipitation. However, this situation has been reversed since the 1980s. It is predicted that precipitation will decrease by 15-40 and 0-10 mm/year in the Inner Mongolia plateau and southern Xinjiang, respectively, whereas it will likely increase by 10-40 mm/year in northern Xinjiang. Additionally, 58-62% of the annual rainfall occurred during summer in the DRC, with precipitation increasing during spring and summer and decreasing in winter. The intra-annual precipitation is becoming uniform, but the inter-annual variability in precipitation has been increasing in the western portions of the DRC. The probability of precipitation during the study period increased by 30% and 22.2% in the extreme-arid zones and arid zones, respectively. Conversely, the probability of precipitation during the study period decreased by 18.5% and 37.5% in the semi-arid zones and semi-wet zones, respectively. It is predicted that the northwest portion of the DRC will become warmer and wetter, while the central portion will become warmer and drier and the northeast portion will be subjected to drought. Copyright (c) 2010 John Wiley & Sons, Ltd.