青藏高原地区上对流层—下平流层区域水汽分布和变化特征

Characteristics of Water Vapor Distribution and Variation in Upper Troposphere and Lower Stratosphere over Qinghai-Xizang Plateau

利用2005-2008年青藏高原（下称高原）地区微波临边探测器MLS（MicrowaveLimbSounder）、高光谱分辨率大气红外探测仪AIRS（AtmosphereInfraredSounder）、ECMWF的ERA-Interim资料，以及NCEP／NCAR再分析数据和NOAAHYSPLIT（Hybrid；Single-ParticleLagrangianIntegratedTrajec-toryModel）轨迹模式资料，讨论了高原上空对流层顶附近的水汽分布和变化特征及高原上空平流层与对流层之间的物质交换。结果表明，3-4月高原南侧对流层顶附近100hPa存在一个水汽低值带，而7-8月和9-10月此处存在一个明显的水汽高值区。3-4月夏季风未发展之前，受高原大地形抬升和西风气流的影响，高原以南地区存在对流层与平流层的物质交换，而215hPa的高原中部地区（80°E-90°E）则由于空气的下沉运动将上层的干空气向下输送而出现一个水汽低值中心。7-8月，受印度夏季风和高原上空反气旋式环流的影响，高原上空有明显的水汽穿过对流层顶向平流层输送，反气旋环流中心的水汽经过2～4天的上升过程可以从对流层进入平流层。高原及其以东、以西地区的水汽在对流层顶附近的季节变化基本一致，100hPa三个不同区域的水汽在3月达到最低。

Using the MLS （Microwave Limb Sounder）, high-spectral resolution AIRS （Atmosphere Infrared Sounder） and ECMWF （ERA-interim） data from 2005 to 20（18, combined with NCEP/NCAR reanalysis data and a trajectory model （NOAA HYSPLIT）, the distributions and sources of atmospheric water vapor near tropo- pause region over the Qinghai-Xizang Plateau （QXP） were investigated and stratosphere-troposphere exchange （STE） over the QXP was expounded. The results show that the distributions of water vapor over the QXP are characterized by a minimum over the southern QXP from March to April, and a maximum over the southern QXP from July to October near tropopause region on 100 hPa. The water vapor mixing ratios have large values in the upper troposphere over the south slope of QXP between MaJrch and April, the resu!ts suggest that transport of air masses from the troposphere to stratosphere occurs over south slope of QXP because of the orographic lifting of QXP and the westerly circulation. The low water vapor on 215 hPa over the center of the QXP （80°E --90° E） is related to the sinking of dry air from the UTLS region. The water vapor over the QXP is the highest in the exuberant monsoon season between July and August and is related to the Indian summer monsoon and anticyclon- ic circulation, which transports water vapor to the lower stratosphere over the QXP through the upward movement of 2 -4 days. The seasonal variation of water vapor mixing ratJios near tropopause region （i. e. , on 100 hPa） is consistent over the QXP, the east and west of QXP, the mininmm value of water vapor occurs in March.