长江上游地区可利用降水量的气候特征

摘要

Based on the observational temperature and precipitation data of 107 stations in the upper Yangtze River basin during 1960 - 2008, the utilizable precipitation was calculated by Takahashi's evaporation equation and the relationship of water balance.The climatic characteristics of utilizable precipitation in the upper Yangtze River basin were studied by means of mathematical statistics, the analysis of REOF and M-K methods. The results showed that the seasonal variation of utilizable precipitation was obvious in the upper Yangtze River basin. The utilizable precipitation in the upper Yangtze River basin from May to September appeared two or three centers and the centers little moved. From October to April, the utilizable precipitation showed a gradual decrease from south to north. The analysis of REOF showed that the spatial distribution of the utilizable precipitation in the upper Yangtze River basin were abnormal in several types: southeast, northeast, middle part, northwest, north and southwest in summer half year. Precipitation played a crucial role in the utilizable precipitation. When the West Pacific Subtropical High(WPSH) shifted northward and westward( southward and eastward) in summer, the utilizable precipitation in the eastern part of upper Yangtze River basin was less (more). The utilizable precipitation in the eastern (northwestern) upper Yangtze River basin was less(more)while the East(South) Asian summer monsoon was stronger(weaker).%利用长江上游地区107个观测站1960-2008年气温、降水观测资料,采用陆面蒸发经验模型计算得到各观测站的月蒸发量,再根据水量平衡关系,得到可利用降水量,采用数理统计、REOF分析和M-K突变检验等方法,分析长江上游地区可利用降水量的气候变化特征.结果表明:长江上游可利用降水量季节变化显著,5-9月长江上游可利用降水出现2-3个高值中心且中心位置稳定少变.10-4月可利用降水基本上呈由南向北逐渐减少的特征.长江上游夏半年可利用降水的空间分布类型可分为长江上游东南区、东北区、中部区、西北区、北部区和西南区.大气降水在可利用降水量中起决定性作用.当夏季西太平洋副热带高压偏北偏西(偏南偏东)时,长江上游东部地区可利用降水量偏少(多);当东亚(南亚)夏季季风偏强(弱)时,长江上游东部(西北部)可利用降水量偏少(多).