关键词: Penman-Monteith模型, 气候干燥度, 夏季风, 气候变暖

Abstract:

Based on the data of monthly precipitation and other monthly meteorological factors of 661 meteorological stations over China from 1961 to 2013. The Hetao area of North China, which is drying significantly, is chosen and its temporal evolution characteristics are studied by using REOF. The effects of the summer monsoon and the meteorological factors on the aridity index (IA) are discussed, and the results are as follows. The summer monsoon index of western South Asian (ISASM1) mainly affects the overall trend and the annual change of climatic dry during 1961-1991. With global warming, the degree of the influence is weakened, and the decadal variation of IA is mostly affected by temperature and other thermal factors. The influence of annual variation of the thermal factors on the IA decreases, while the influence of decadal variation of the thermal factors on the IA increases after the 20th century. It shows that climatic warming causes the increasing vapor pressure difference, the decreasing relative humidity. Air needs more vapor to be saturated, while increasing evaporation in surface, air drying degree, and arider climate in Hetao area of North China.

Key words: Penman-Monteith model, aridity index, summer monsoon, climatic warming