摘要
选取了1961—2007年青藏高原海拔2 000 m以上76个气象站夏季(6—9月)逐日地面降水观测资料,分析了青藏高原夏季夜雨率的时空特征,结果表明:1.青藏高原夜雨率具有显著的区域差异性,在西藏中西部夜雨率呈"纬向型"分布,而西藏东部、川西高原至滇北夜雨率则表现为"西北-东南"走向;夜雨率高值中心出现在雅鲁藏布江中段(日喀则地区东北部至拉萨市一带),达到75%以上,同时喜马拉雅山脉南麓可能是夜雨率>70%的另一个高值区域;夜雨率最低值在青海省西北部,仅为33%;2.高原夜雨率具有明显的海拔效应,夜雨率与海拔呈显著的反相关,即海拔越高夜雨率越低,反之亦然;3.高原夜雨率随夏季日期推后呈增大趋势,而年际变化上则表现为明显的下降趋势2,0世纪80年代初存在明显的突变现象;4.高原夜雨率与日降水量之间存在一定的关联:当日降水量<1 mm时夜雨率仅为48.8%,此后夜雨率随着日降水量增加而明显增大,特别是降水量在20 mm以下时,夜雨率上升速度最快,上升幅度超过20%;当日降水量为23～40 mm时,夜雨率稳定在70%～76%间,随后又略有波动下降;当日降水量为33 mm时,夜雨率达到极大值,为75.1%。青藏高原夜雨率的空间变化可能受大地形的影响。高原夜雨对农牧业生产有利的同时,也可能会带来诸多自然灾害。因此,深入探讨夜雨率是制定有效防御气象灾害对策的重要依据。
Using daily precipitation data at the 76 meteorological stations（above 2 000 m a.s.l.） during summer（June to September） from 1961 to 2007 over the Tibetan Plateau,spatial and temporal variations of the night-rain are investigated.The results suggest that： 1.There are significant regional differences for the night-rain rate in the Tibetan Plateau.a latitude-type distribution appears in central and western Tibet,and a northwest-southeast distribution exists in the eastern Tibet,western Sichuan to northern Yunnan.Those distribution may be caused by huge terrains in the Tibetan Plateau.The highest value centers are located in the middle of the Yarlung Zangbu River basin（more than 75 %） and possibly in the southern slope of the Himalayas（70 %）,while the lowest value appears in the northwest of Qinghai Province（around 33%）.2.The night-rain rate has a significant negative correlations with elevation.3.The averaged daily night-rain rate increases with the summer date,while annual average night-rain rate show a decrease trend during last 40 years and the change point happened in the early of 1980s.4.The night-rain rate is also related with daily precipitation.The night-rain rate is only 48.8 % when the daily precipitation is less than 1 mm,then it increases remarkably with precipitation increasing,especially when precipitation is below 20 mm.When daily precipitation is between 23 to 40 mm,night-rain rate maintains stably at 70 to 76 %,then follows by a slight decline;it reaches maximum value（75.1 %） when daily precipitation is 33 mm.
出处
《山地学报》
CSCD
北大核心
2011年第5期627-632,共6页
Mountain Research
基金
2009年西藏自治区重点科技应用基础研究项目(200910-11)~~
关键词
夜雨率
时空变化
青藏高原
night-rain rate
temporal and spatial variation
Tibetan Plateau
