Drying Trend in Northern China and Its Shift during 1951-2016

There are significant changes in precipitation over China under global warming. During 1951-2000, the precipitation experienced a period when its spatial distribution showed a pattern of 'western wetting and eastern drying, WWED'in northern part of China and 'southern flooding and northern drought, SFND' in eastern part of China. Does this distribution pattern of long-term precipitation change still maintain or change after 2001? Based on observations of monthly mean temperature, monthly mean precipitation, and calculated self-calibrating Palmer Drought Severity Index (scPDSI) and surface wetness index (SWI), the drying trend in China has been revisited. Results show that the wet-dry spatial distribution in China has been changing significantly after 2001. Over northern China, the pattern of WWED switched to 'western drying and eastern wetting, WDEW'; over eastern China, the pattern of SFND changed to 'southern drought and northern flooding, SDNF' during 2001 to 2016. In central part of northern China, precipitation trend switched from a decreasing trend to a significant increasing trend; precipitation in the upper and middle reaches of Yangtze River experienced a shift from significant increasing trend to a decreasing trend. However, according to the analysis of Terrestrial Water Storage (TWS) data of The Gravity Recovery and Climate Experiment (GRACE), the wet-dry pattern of SFND over eastern China has not changed during 2001-2016, and the drying trend in northern China has been intensifying since 2001. This is opposite to the results shown in precipitation. The reason will be studied in the future.