1998年和2010年夏季长江流域降水低频变化及水汽输送特征对比分析

Comparative Analysis of the Characteristics of the Low-Frequency Precipitation and Low-Frequency Water Vapor Transport over Yangtze River during Summer in 1998 and 2010

摘要: 利用长江流域夏季降水资料和NCEP/NCAR再分析资料、NOAA海温等资料，对比分析了1998年和2010年夏季降水异常特征，探讨了不同分布型厄尔尼诺事件背景下长江流域典型涝年夏季低频降水特征及其低频水汽输送差异。结果表明，1998年长江流域全流域性多降水，而2010年降水偏多区域主要集中在长江中下游地区。1998年夏季长江流域降水存在8~15 d和30~50 d的显著低频周期，来自阿拉伯海、孟加拉湾的西南低频水汽输送及沿着副高西南、西北边缘来自西太平洋、南海的东南低频水汽输送对该年长江流域夏季8~15 d低频降水的发生和维持有着显著的作用；而2010年长江流域夏季降水存在10~20 d和30~60 d的显著低频周期，来自西太平洋的偏东低频水汽输送和沿副高西南侧北上的东南低频水汽输送对该年夏季长江流域10~20 d低频降水的发生和维持有着显著的作用。

Abstract: In this study, summer rainfall anomalies in China in the two years are compared by using the summer rainfall dataset in the Yangtze River, NCEP/NCAR reanalysis data, NOAA sea surface temperature data and so on, revealing the characteristics and the differences in low-frequency water vapor transport of the summer low-frequency precipitation of typical flood years in the Yangtze River under the background of the different type of El Nino events. The results show that the whole basin multi-precipitation occurred in the Yangtze River in 1998 while the region of more rainfall is mainly concentrated in the middle and lower reaches of the Yangtze River in 2010. There is a significant low-frequency period of 8 - 15 d and 30 - 50 d during the phase of the summer rainfall in the Yang-tze River in 1998. The southwest low-frequency water vapor transport from the Arabian Sea, the Bay of Bengal and the one from the western Pacific, South China Sea along the southwest, northwest edge of the western Pacific subtropical high play an important role in the development and maintenance of the 8 - 15 d low-frequency precipitation period in summer in the Yangtze River in 1998. In contrast, there is a significant low-frequency period of 10 - 20 d and 30 - 60 d during the phase of the summer rainfall in the Yangtze River in 2010. The east low-frequency water vapor transport from the western Pacific and the northward southeast one along the southwest edge of the western Pacific subtropical high play an important role in the development and maintenance of the 10 - 20 d low-frequency precipitation period in summer in the Yangtze River in 2010.