夏季东亚季风区水汽输送特征及其与南亚季风区水汽输送的差别

Characteristics of the Water Vapor Transport in East Asian Monsoon Region and Its Difference from that in South Asian Monsoon Region in Summer

利用ＥＣＭＷＦ所分析的１９８０～１９８９年每日各层的水汽和风场资料分析了东亚季风区夏季风的水汽输送特征，并与印度季风区夏季水汽输送进行比较。分析结果表明了东亚季风区夏季水汽输送特征明显不同于印度季风区夏季水汽输送，东亚季风区夏季水汽输送经向输送要大于纬向输送，而印度季风区夏季水汽输送则以纬向输送为主。分析结果还表明东亚季风区由于夏季水汽分布是南边大、北边小，偏南季风气流所引起的水汽平流是湿平流。因此，水汽的辐合主要由季风气流所引起的水汽平流所造成，而印度季风区季风气流所引起的水汽平流是干平流，它利于水汽输送的辐散，水汽的辐合主要是由于风场的辐合所造成。

The characteristics of the water vapor transport by the summer monsoon in the East Asian monsoon region is analysed by using the daily data of water vapor and wind fields at various levels analysed by ECMWF, and its difference from that in the Indian monsoon region is compared in this paper. The analysed results show that there is a obvious difference between the characteristics of the water vapor transport in the East Asian monsoon region and those in the South Asian monsoon region in summer. In summer, the meridional water vapor transport is larger than the zonal water vapor transport in the East Asian monsoon region, but the zonal water vapor transport is dominant in the Indian monsoon region. Moreover, the analysed results also show that due to the distribution of water vapor in the East Asian monsoon region: large in the south and small in the north, the water vapor advection by the southerly monsoon flow is wet advection. Therefore, the convergence of the water vapor transport is mainly due to the water vapor advection caused by the monsoon flow in the East Asian monsoon region. However, in the Indian monsoon region, the water vapor transport is dry advection, which assists the divergence of water vapor, thus, the convergence of water vapor is mainly caused by the convergence of wind field.