近30年西藏地区大气可降水量的时空变化特征  

Spatial and Temporal Changes of Atmospheric Precipitable Water in Tibet Region in Recent 30 Years

作　　者：卓嘎[1,2] 边巴次仁[3] 杨秀海[2] 罗布[1] 

机构地区：[1]中国气象局成都高原气象研究所拉萨分部,西藏拉萨850000 [2]西藏高原大气环境科学研究所,西藏拉萨850000 [3]西藏自治区气象局,西藏拉萨850000

出　　处：《高原气象》2013年第1期23-30,共8页Plateau Meteorology

基　　金：中国气象局新技术推广项目(CMATG2010M24);公益性行业专项(GYHY201006054);甘肃省科技重大专项(1001JKDA001);川气课题(2012-青年-03);国家自然科学基金项目(41130960)共同资助

摘　　要：利用1980—2009年NCEP/NCAR再分析资料以及同期西藏地区34个气象站的月降水量资料,分析了该地区大气可降水量和降水转化率的时空变化特征。结果表明:(1)该地区大气可降水量具有从东南向西北逐渐递减的空间分布特征;近30年大气可降水量呈逐渐减少趋势且年际变率相对较小,还表现出显著的季节差异,即夏季大气可降水量最大、冬季最小;多、少雨年大气可降水量的空间差异不显著,说明西藏地区的空中水汽含量相对稳定,有利于空中水资源的合理开发和利用。(2)降水转化率在那曲中东部和西藏东南部最高、西藏西北部最低;近30年西藏地区降水转化率呈逐渐增加趋势且年际变率较大,其季节变化与大气可降水量的变化规律一致;降水转化率的高低在一定程度上决定了某年为多(少)雨年。(3)西藏地区大气可降水量和实际降水量的空间分布规律接近,但其时间变化趋势与同期降水量增加的趋势正好相反;大气可降水量转化率与实际降水量的变化趋势基本一致,降水转化率的升高(降低)对应着降水量的增多(减少)。The spatial and temporal distributions of atmospheric precipitagle water （APW） and precipi- tation conversion efficiency （PCE） in Tibet region were investigated using NCEP/NCAR reanalysis data with monthly precipitation at 34 meteorological stations from 1980 to 2009. The results show that. （1） APW is gradually decreasing from southeast to northwest parts of Tibet region, APW during the recent 30 years has decreasing and its interannual variability is relatively small, which appeared an obvious seasonal difference, the maximum value was in summer and the minimum value was in winter. There is no more difference for the amount of APW between more and less rain years indicating that the water content in the air is relatively stable in Tibet region, which is beneficial to its reasonable exploitation and utilization. （2） The highest PCE in Tibet region is in the middle and the eastern parts of Nagqu and the southeast part of Nyingchi, while the lowest PCE is in the northwest of Tibet. PCE appears the increasing trend during the recent 30 years and the interannual variability is relatively large while it has same seasonal variation as APW. The amount of the PCE determines the year will be more rain year or less rain year to some extent. （3） The spatial distribution of APW is quite similar with the distribution of natural precipitation, but it has opposite temporal variation trend to the increasing trend of precipitation while PCE has basically same variation trend as natural precipitation during the recent 30 years. The ascending （descending） of the PCE is corresponded to the increase （decrease） of precipitation.

关 键 词：西藏地区 大气可降水量 降水转化率 

分 类 号：P426.61[天文地球—大气科学及气象学]