The Progress of Dry–wet Climate Divisional Research in China

The dry–wet climate regionalization index, potential evapotranspiration calculation methods, standard and named methods of dry–wet climate regionalization, etc., since the middle of the 20th century are reviewed in this paper. Using the arid index, climate regionalization and class standards were given on the basis of former review. Then, the characteristics of wet–dry climate division were analyzed using observed data at 2207 national meteorological stations from 1981 to 2010. The results showed that the total arid area (including extreme arid, arid and semi-arid areas) was 4.692 million hm2 in China, accounting for 48.8% of the land area in China, which included 878,000 hm2 (9.1%), 2.092 million hm2 (21.8%) and 1.722 million hm2 (17.9%) for extreme arid, arid and semi-arid area, respectively. The arid areas were mainly distributed in Xinjiang, Inner Mongolia, Tibet, Qinghai, Gansu and other western regions. Sub-humid area, wet area and excessive wet area accounted for 1.6%, 27.8% and 8.8% of China’s land area, respectively, mainly located in the south of the Yangtze River and Northeast China. Since 1961, the overall characteristics of dry-wet climate change in China are that the total arid areas shows a decreasing trend, while the total wet areas shows an increasing trend.