基于QuikSCAT资料的江淮流域旱涝年南海季风变化特征

CHARACTERISTICS OF THE SOUTH CHINA SEA MONSOON IN DROUGHT/FLOOD OF THE YANGTZE RIVER-HUAIHE RIVER VALLEY DETERMINED WITH THE QUIKSCAT DATA

利用2001、2003年的Quik SCAT风场和中国降水的逐日资料,分析江淮流域旱、涝年南海夏季风的演变特征及其低频分量与江淮流域降水的关系。结果表明:(1)2001、2003年南海夏季风爆发时间相当,但2003年6月中下旬季风出现明显的中断,2001年6—7月南海季风表现出明显的由南海中南部向北部推进的过程,而2003年同时期的季风则徘徊于南海中南部地区;(2)2001、2003年的夏季(5—9月)海表面的低频纬向风场同时都存在3对低频振荡中心,且在季风爆发后均有明显的向北传播特征,南海中部和北部表现出近乎相反的低频位相,但2001年低频振荡的强度及低频波列维持的时间均大于2003年的;(3)根据纬向风低频振荡强中心区域的位置,在南海中部和北部分别定义了南海低频夏季风指数IM-SCS和IN-SCS,发现这两个指数与我国6—7月江淮流域的降水及青藏高原中东部降水之间均存在显著的滞后负相关关系,而与云南中部、西部及华北部分地区的降水则表现出显著的滞后正相关关系。

Based on the QuikSCAT data of 2001 and 2003, the variation characteristics of South China Sea summer monsoon and the relationship between its LFO components and the rainfall in Yangtze River-Huaihe River basin are analyzed for its drought/flood years. The results are shown as follows. （1） In 2001 and 2003, the onset of South China Sea monsoon took place at nearly the same time, but the monsoon was interrupt in the middle of June, 2003. In 2001, the monsoon advanced northward and its center rapidly moved from 8N to the northern part of the South China Sea, while in the same period of 2003, the monsoon was wandering about in the central-south of the South China Sea. （2） In the two years, there were three pairs of oscillation centers which propagated northward significantly and displayed almost opposite LFO phase in the low-frequency wind field, but in terms of intensity and duration, the 2001 monsoon is stronger and lasted longer than that of 2003. （3） The IM-SCS and IN-SCS are defined, according to the location of the strong center regions of low-frequency wind, and a pronounced, negative lagging-correlation is found between the indices and the rainfall of June and July in the Yangtze RiverNHuaihe River basin and in the middle and east parts of Tibetan Plateau. However, the relationship between the low-frequency monsoon index and the rain of the middle and western parts of Yunnan Province and some of the North China region show a pronounced, positive lagging-correlation.