【摘要】 用中国西部１０省区（１１０°Ｅ以西）１３０个站的月降水资料，分析夏半年４—１０月的月降水相对系数、月际和年际标准差变化特征。结果表明，各地区受不同降水体系影响，降水在时空上的差异很大。天山北部主要受西风带降水体系影响，月际降水差异不大；西北地区受西太平洋副热带高压雨带影响，降水具有西进北抬尔后东退南辙的特征；高原季风雨带对四川西部、云南和西藏有明显影响，雨季从东南向西北开始，而结束与此相反。月际和年际标准差表明，在以南疆盆地为主的东北—西南一带地区的标准差为高值区，而该地区以东和以北地区的标准差呈逐渐减小趋势更多还原

【Abstract】 The monthly precipitation data observed at 130 stations in Northwest Chinawere applied in this paper.The variation features of the monthly precipitation relative coeffi cient,the intermonthly and the interannual standard deviations during April to October wereanalysed,respectively.The northern Tian Mountain was mainly affected by western wind,itsintermonthly standard deviations were small.The Northwest China was obviously influencedby the rain systems produced from northern pacific high pressure,its rain had a feature thatfrom southeast to northwest,afterwards,it moved backward.Plateau monsoon had influenceson the west Sichuan,Yunnan and Xizang.The rain started from Batang and ended at the west of Xizang,then they moved backward.Theintermonthly and interannual standard deviationsspecified that Nanjiang Basin had higher values,and other areas decreased gradually awayfrom Nanjiang Basin.更多还原