中国西北东部近50 a降水异常分布及变化特征

Characteristics of Precipitation Anomalies in the Last 50 Years in Eastern Part of Northwest China

基于主成分分析和旋转主成分分析方法,应用陕、甘、宁、青4省（区）170个测站的降水量观测资料,分析了西北东部1961-2010年降水量区域分布、地域相关和年际变化特征。结果表明：西北地区东部降水异常在空间上主要表现为较高的整体一致性,其次表现为东西相反和南北相反的变化趋势。西北地区东部降水异常存在4个基本相关的区域：陇东南和陕西中南部区、陇中宁夏和陕北区、青海高原区和河西走廊区。近50 a来,陇中宁夏和陕北区、河西走廊区各年代降水呈反位相变化;陇东南和陕西中南部区、青海高原区1961年以来的前40 a各年代变化趋势一致,本世纪初的10 a变化相反。河西走廊区、青海高原区则向湿转变,陇中宁夏和陕北区、陇东南和陕西中南部区干旱程度更为明显。

Based on principal component analysis and rotated principal component analysis methods,the spatial distribution,correlation regions and interannual variability characteristics of precipitation from 1961 to 2010 in east part of northwest China were analyzed by using the observation data of 170 stations from Shaanxi,Gansu,Ningxia and Qinghai.The results show that the precipitation anomaly in east part of northwest China presented mainly overall consistency firstly,secondarily,it followed opposite change trend in the east and the west as well as the south and the north part.There were four related areas of precipitation anomaly in east part of northwest China including the area in southeast of Gansu and the central and southern Shaanxi（area I）,the area in central Gansu,Ningxia and north of Shaanxi（area II）,the area in plateau of Qinghai（area III） and Hexi Corridor（area IV）.In recent 50 years,precipitation of the area II and IV presented reverse phase change in each decade.While,the variation trend of precipitation in the area I and III was consistent from 1961 to 2000,but their changes were opposite in the 2000 s.The climate turned to be wet both in the area III and IV and to be more significant drought in the area I and II.