夏半年青藏高原“湿池”的水汽分布及水汽输送特征

Characteristics of the Moist Pool and Its Moisture Transports over Qinghai-Xizang Plateau in Summer Half Year

采用1948-2007年共计60年的NCEP/NCAR再分析资料,计算了夏半年(4-9月)青藏高原大气中的可降水量、水汽输送通量和水汽输送通量散度,分析了夏半年青藏高原可降水量的分布和变化特征,青藏高原及其附近的水汽输送。结果表明:在对流层中层的青藏高原上空,夏季是一个明显的大气水汽含量高中心,"湿池"特征非常显著,湿池主要有三个大的可降水量中心,即高原的西南部、东南部和高原南侧。4-9月,高原上的可降水量变化很大,高原的增湿的速度小于减湿的速度。水汽进入高原主要通过三条水汽通道,即西风带水汽输送通道、印度洋—孟加拉湾水汽通道和南海—孟加拉湾水汽通道。水汽主要在高原西南侧、喜马拉雅山中段和高原东南侧进入高原。

The precipitable water vapor, transfer flux of water vapor and divergency of transfer flux of water vapor over the Qinghai-Xizang Plateau in summer half year （from April to September） is calculated by using NCEP/NCAR reanalysis data obtained from 60 years from 1948 to 2007. The distribution and variation characteristic of precipitable water vapor in summer half year over the Qinghai-Xizang Plateau is analyzed. The transfer of water vapor over the whole plateau and its surrounding is analyzed. THe result shows that there is a significant high center of precipitable water vapor at the middle troposphere over the Qinghai-Xizang Plateau in summer half year. The characteristics of ＇moist pool＇ are significant, and there are three high centers of precipitable water vapor in the ＇moist pool＇ , which are southwest, southeast and south sides of the plateau. The variation of pricipitable water vapor over the whole region is great from April to September. The velocity of moisture increase is faster than its decrease. Water vapor comes into the Qinghai-Xizang Plateau mainly through three moisture channels, which are westerly zone channel, Indian Ocean via the Bay of Bengal channel and South China Sea via the Bay of Bengal channel. The water vapor entering the plateau is mainly from the southeast plateau, the southwest plateau, and the middle Himalaya Mountains.