【作者】 丁斌；

【导师】 缪启龙；

【作者基本信息】 南京信息工程大学 ， 气象学， 2006， 硕士

【摘要】 本文采用中国743个测站的月降水量观测资料及NCAP/NCAR再分析资料,首先分析了西部地区整层、500Hpa单层比湿及水汽输送通量的分布特征;将我国西部地区划分为西北东部区、西北中部区、南疆区、北疆区、西藏区及青海六个区,分析各区夏季降水与水汽关系及旱涝异常特征,揭示了中国西部地区水汽的来源;最后重点讨论了青藏高原南、北两区的降水变化特征及水汽的来源,得到以下主要结果: (1)水汽的垂直分布结构比较相似,850Hpa至300Hpa各层的水汽分布中心主要位于青藏高原附近。其季节变化的特点是:夏季比湿最大,春季次之,冬季最小。 (2)从整层水汽输送通量来看,春季西部地区水汽主要来自中亚地区;夏季孟加拉湾的水汽通过河谷输向高原东南部及南海,西部地区的水汽主要来自大陆内部的向东输送;秋季高原的水汽来自高原的西部及孟加拉湾,西部其它地区基本上一致为西风输送;冬季整个大陆为比较一致的西风输送。500Hpa我国西部地区的水汽输送以纬向输送为主,西南地区的水汽主要来自西南季风输送,西北地区的水汽主要来自西风带输送。 (3)西北东部区夏季降水与春、夏季比湿及水汽通量相关的分析,揭示影响该区夏季降水的水汽主要来自西风输送及中纬度西太平洋。在西北东部区夏季干旱年来自中纬度的西风带水汽输送增强;而夏季湿润年高原东部向北的水汽输送明显增强。我国西北地区中、西部的夏季降水与春、夏季比湿及水汽通量相关的分析,揭示这些地区的水汽仍主要来自于北大西洋、北冰洋的西风输送。 (4)总的来说青藏高原整个地区的降水量在40多年来是增加的,其中1961—1980年是少雨期,1981—2000年是多雨期。高原春季和冬季降水量呈增加的趋势,夏季和秋季的降水量变化比较平稳。青藏高原南区降水量也呈增加的趋势,北区降水量没有明显的变化。 (5)西藏夏季降水与春、夏季比湿及水汽通量相关的分析,揭示影响该区夏季降水的水汽主要来自低纬海洋及西风输送。在夏季干旱年,西风的水汽输送减少,孟加拉湾的向北的输送明显减弱,在我国西南地区水汽向北输送减弱;在夏季湿润年,北印度洋向东北的水汽输送及经高原主体的西风输送明显增强,孟加拉湾的向北水汽输送也显著增加。 (6)青海夏季降水与春、夏季比湿及水汽通量相关的分析,揭示该区夏季降水的水汽来自南海、我国东部地区海域。在夏季干旱年,高原上向东输送增强,其以北地区西风输送减弱,而南海、孟加拉湾向大陆的西南水汽流转向后向东输送增加,向北输送减弱;在湿润年,高原东部水汽向北输送增强,尤其是我国中、东部的水汽向西输送及华北的向东输送增强,这似乎与副高的水汽输送增强有关。更多还原

【Abstract】 By using of monthly rainfall of 743 stations and NCEP/NC AR reanalysis monthly data , firstly , the distribution characters of whole layer and 500Hpa monolayer specific humidity and vapor transportation fluxes in west China are analysed;secondly , dividing the west China into the eastern northwest ,the central northwest, southern Xinjiang , northern Xinjiang , Tibet , Qinghai , the paper analyses the relation of the rainfall in summer and water vapor , discusses the abnomal characters in drought/flood years , reveals the sourses of water vapor in western regions;lastly, puts the emphase in the rainfall and water vapor of Qinghai-Tibet Plateau composed of north and south parts . The results are that:(1) The vertical distribution of water vapor from 850Hpa to 300Hpa are resemblance , whose centers are located in near the Qinghai-Tibet Plateau . The changeable features of specific humidity in season are : it is biggest in summer, less in spring , least in winter.(2) In spring , the whole layer vapor transportation fluxes of west China are mainly from mid-Asia;in summer , the water vapor of the bay of Bengal is stronger , there is lots of vapor through the stream valley to the southeast of Qinghai-Tibet Plateau and the south China Sea . In this time , the vapor in west China is lesser , moreover , principally comes from the inland of China and transits to the east;in autumn , the vapor of Plateau is from its western regions and the bay of Bengal , other areas are almost westerly vapor transportation;the vapor is least in winter and nearly westerly transportation .In 500Hpa , the averagely vapor transportation in west China are mainly in zonal transport . The vapor of southwest is from southwest monsoon, and the vapor of northwest comes from westerly transport.(3) The correlation of the rainfall of eastern northwest in summer and water vapor reveals that the rainfall is mainly from westerly vapor transportation and mid-latitude Pacific Ocean . meanwhile, it is relation to the vapor of the low-latitude Ocean . in its drought years , the westerly vapor transportation in mid-latitude amplify obviously , while in flood years northward vapor transport of Plateau eastern areas strengthen . The result shows the precipitation in summer of eastern northwest is related to southwest vapor transport . The correlation of rainfall of the mid-west northwest in summer and water vapor shows the rainfall comes from the westerly vapor transport of the Atlantic Ocean and the Arctic Ocean .(4) Totally, the rainfall of Qinghai-Tibet Plateau increases during the last four decades , in which the years 1961-1980 is less rain perid , 1981-2000 is morerain perid . In spring and winter the rainfall of Plateau is increasing tendency , while in summer and autumn the rainfall changes little . The rainfall of the southern Plateau also presents increasing tendency .(5) The analysis to the correlation of the rainfall in Tibet and specific humidity & vapor transportation fluxes reveal that the vapor in spring from the low-latitude ocean has some impacts to the precipitation in summer , and the vapor in summer that impacted the area is from the low-latitude ocean and westerly transport. In the drought years , the westerly vapor transport and the northward vapor transport from the bay of Bengal weaken obviously , while in the flood years , the vapor toward northeast from the north Indian Ocean and the westerly vapor transport strengthen , the northward vapor from the bay of Bengal strengthen obviously too .(6) The analysis to the correlation of the rainfall in Qinghai and specific humidity & vapor transportation fluxes reveal that the vapor in summer is from the south China Sea and the north china , In the drought years , the eastward vapor transport from the Plateau strengthen , while the westerly vapor transport from the north of Plateau weaken . In the flood years , the vapor toward north from the Plateau strengthen , maybe it relates to the reinforcement of subtropical high.更多还原