长江流域年降水量的空间特征和演变规律分析

Spatial characteristics and evolutional trends of annual precipitation in the Yangtze River basin

为获取长江流域年降水量的时空变化特征，对长江流域年降水量进行了空间分区和时间演变分析．根据长江流域146个气象站点1960—2005年的逐年降水量资料，采用经验正交函数和旋转经验正交函数对长江流域年降水量的空间变化特征进行分析，并计算了1960—2005年年降水量的线性演变规律，利用奇异谱分析方法来检测区域降水量发生突变的情况．结果表明，长江流域年降水量主要有3种空间分布型、8个降水变化敏感区域．8个敏感区域中，汉江流域、岷江-嘉陵江源区、乌江流域南部年降水量呈减少趋势，其中岷江-嘉陵江源区减少最为显著，年降水量每10年减少27．1mm；洞庭湖-鄱阳湖地区、鄱阳湖流域南部、太湖流域、金沙江流域中部、云南地区年降水量呈增加趋势，其中金沙江流域中部年降水量显著增加，年降水量每10年增加17．7mm．存在降水突变的地区有5个，下游的太湖流域发生最早，时间为1977年，上游云南地区最晚，为1998年．长江流域年降水量有比较明显的空间区域特征，各个区域年降水量的时间演变规律也不一致．

To get its spatial and temporal characteristics, the spatial zoning and evolutional trends of the annual precipitation in the Yangtze River basin were analyzed. Based on the preeipitation data of 146 meteorological stations in the Yangtze River basin from 1960 to 2005, the spatial eharaeteristies were calculated by use of the empirieal orthogonal function and the rotated empirical orthogonal function, the linear evolutional trends of the annual precipitation from 1960 to 2005 were analyzed, and the abrupt changes were deteeted by means of the singular speetrum analysis. The results show that, the annual precipitation in the Yangtze River basin has 3 main spatial distribution patterns and 8 sensitive areas. Among the 8 sensitive areas, the annual precipitation in 3 areas （Hanjiang River basin, Minjiang River-Jialing River source area, south of Wujiang River basin） have decreased, espeeially that in the Minjiang River-Jialing River source area has a decrease of 27.1 mm per 10 years; the annual precipitation in 5 areas （Dongting Lake-Poyang Lake area, south of Poyang Lake basin, Taihu Lake basin, center of Jinsha River basin, Yunnan area） have increased, especially that in the center of Jinsha River basin has an increase of 17.7 mm per 10 years. There are 5 areas with abrupt changes. Among them, the Taihu Lake basin in the lower reaches of Yangtze River had the earliest abrupt changes in 1977, while the Yunnan area in the upper reaches of Yangtze River had the latest ones in 1998. The annual precipitation in the Yangtze River basin has obvious spatial regional characteristics, and its temporal evolutional trends in various areas are different.