长江流域不同类型降水量的非均匀性分布特征

基于长江流域1963~2016年131个气象站点逐日降水资料，计算了年降水、强降水（极端降水和暴雨）的集中度（PCD）、集中期（PCP），并结合M-K非参数性趋势检验分析以及相关分析等方法对长江流域降水非均匀性分布特征及其趋势进行了分析，目的在于揭示不同类型降水量在流域内非均匀性分布的特征，加强对强降水在时空分布上的理解。结果表明：流域多年平均年内日降水量集中度（PCDDP）、集中期（PCPDP）均由下游向上游递增，PCDDP变化趋势不显著而PCPDP变化趋势在空间上差异明显，在流域中下游呈增长趋势、上游呈减小趋势；年降水量与PCDDP呈显著正相关的地区主要分布在四川盆地；流域年极端降水量PCDEP、PCPEP的多年平均分布及变化趋势与PCDDP、PCPDP相似。流域多年平均暴雨量（日降水≥50 mm）从下游向上游递减，在四川盆地较四周高，暴雨在流域东部呈增长趋势，在四川盆地呈减小趋势；年暴雨量集中度（PCDRP）、集中期（PCPRP）从流域东南向西北递减，在湖北、贵州以及四川东部PCDRP呈增加趋势，在流域东南部呈减小趋势；PCPRP在江浙、安徽、湖南及贵州地区呈不明显的增加趋势，在四川、云南等地呈减少趋势。

Inhomogeneity Distribution of Different Types of Precipitation in the Yangtze River Basin

Based on the daily precipitation data collected from 131 meteorological stations in the Yangtze River Basin during 1963-2016, precipitation-concentration degree (PCD) and precipitation-concentration period (PCP) of annual precipitation and heavy precipitation (extreme precipitation and rainstorm) were calculated, respectively. Meanwhile, the M-K nonparametric trend test and correlation analysis methods were used to analyze the inhomogeneity and the variation trend of precipitation in this area. The aims of this study are to characterize the inhomogeneity of different types of precipitation in this basin, and enhance our understanding of spatial and temporal distribution for heavy precipitation. The results showed that multi-year mean annual PCDDP and PCPDP increased from the lower to upper reaches. The variation trend of PCDDP was not significant. For PCPDP, its spatial variation trend was obviously different, an increasing trend occurred in the middle and lower reaches, while a decreasing trend appeared in the upper reaches. There was a significant positive correlation between annual precipitation and PCDDP, which mainly distributed in Sichuan Basin. The multi-year mean annual PCDEP and PCPEP and their variation trends were similar to that of PCDDP and PCPDP. The multi-year mean annual rainstorm precipitation (daily precipitation≥50 mm) decreased from the lower to upper reaches, while it was higher for Sichuan Basin than that in the surrounding area. The variation trend of rainstorm increased in the east of the Yangtze River Basin and decreased in Sichuan Basin. The multi-year mean annual PCDRP and PCPRP decreased from southeast to northwest of the Yangtze River Basin. However, PCDRP increased in Hubei, Guizhou and eastern Sichuan, and decreased in southeastern of the basin. An increasing trend (but not significant) for PCPRP was found in Jiangsu and Zhejiang, Anhui, Hunan and Guizhou, while a decreasing trend was observed in Sichuan and Yunnan.