2004年南海夏季风活动概述

A REVIEW OF ACTIVITIES OF SUMMER MONSOON OVER SOUTH CHINA SEA IN 2004

利用NCEP逐日再分析资料、向外长波辐射(OLR)和卫星降水资料,分析了2004年影响南海夏季风活动的一些特征。结果表明,2004年由于西太平洋副热带高压主体位置比正常偏北、偏西,导致南海夏季风爆发日期比正常偏晚(5月19日)、强度偏大,并主要在南海地区活动。南海季风爆发期间存在明显的季节内振荡,有两个显著振荡周期:一个峰值为20～30天,另一个峰值为40～50天。南海夏季风期间,主要的水汽通量输送集中在南海-西太平洋地区,向北到达华南的水汽输送减少,致使华南地区干旱。

Based on daily NCEP reanalysis data, OLR and satellite rainfall data, the characteristic of the activities of South China Sea summer monsoon（SCSSM） in 2004 were analyzed. The results showed that the establishment of SCSSM was little later than normal and the intensity was stronger than normal. Influenced by the location of the northwest Pacific subtropical high, which was much northward and westward than normal, SCSSM was active mainly in the South China Sea areas. There existed obvious intraseasonal oscillation and two significant periods of SCSSM, one was about 20-30 days, the other about 40-50 days. The transportation of the moisture was concentrated on the South China Sea and the northwest Pacific regions, reducing the northward transportation and resulting in drought in southern China.