华北河套地区气候干燥度的影响因素研究

利用中国1961-2013年661个气象台站观测资料以及亚洲夏季风指数，通过旋转正交分析（REOF）等方法，选择华北河套干旱气候区的代表站，分析了该区域气候干燥度的变化特征，发现该地区整体呈现干旱化趋势。在此基础上讨论了夏季风与气象因子对气候干燥度的影响，结果表明，南亚西区夏季风的年际及整体减弱趋势对华北河套地区气候干燥度的年际趋势变化影响最为显著，主要影响期在20世纪90年代之前，随着区域气候变暖，这种影响程度减弱。各气象要素对气候干燥度的影响存在年际与年代际差异，热力因子的年际变化对干燥度影响较小，而热力因子的年代际变化在20世纪90年代之后对干燥度的影响十分显著。这说明区域气候长期变暖导致当地水汽压差增大，相对湿度减小，空气需要更多的水分才能达到饱和，同时增大了潜在蒸发能力，加剧了华北河套气候区的干旱化。

Study on the Main Factors of Aridity in Hetao Area of North China

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.