苏门答腊地区对流活动及其与南海夏季风建立的关系

Characteristics of Convection Activities over Sumatra Area and Its Relationship with SCS Summer Monsoon Onset

摘要:

使用日本气象厅提供的1980-1997年T_BB资料和NCEP/NCAR40a逐日再分析资料,分析了苏门答腊地区对流活动特征及其与南海夏季风建立的关系,发现南海夏季风的建立与冬季位于苏门答腊的对流中心由冬入夏沿"大陆桥"和中南半岛的系统性移动有密切联系。苏门答腊地区对流沿"大陆桥"移动加快是一个先兆信号,正是对流移动的突然加速,对随后中南半岛对流增强有直接影响;中南半岛地区对流爆发引起副热带高压带在该地区断裂从而导致了南海地区对流活跃和夏季风的建立。南海夏季风爆发之前,南海地区与苏门答腊地区的对流呈偶极型分布;南海地区和苏门答腊南部地区的对流变化几乎呈反相关关系,南海夏季风爆发之前,苏门答腊南部地区对流旺盛;南海地区对流增强期间,苏门答腊南部地区对流减弱。由此可以把南海地区与苏门答腊南部T_BB之差小于等于5K(并维持1候)的开始日期作为南海夏季风爆发的指标之一。

关键词:苏门答腊;对流;";大陆桥";;中南半岛;南海夏季风

Abstract:

Based on 1980-1997 T_BB data from the GMS of Japan and the NCEP/NCAR daily reanalysis data(1958-1997),an investigation is carried out of characteristics of convection activities over Sumatra area and its relationship with the South China Sea summer monsoon(SCSSM) onset.The results show that the onset of the SCSSM bears a close relation to the systematic moving of the convection center over Sumatra along the "land bridge" and Indo-China Peninsula from winter to summer.The sudden acceteration of convection shift affects directly the subsequent enhancement of the convection over Indo-China Peninsula area followed by the rupture of the subtropical high band in this region,leading to the SCSSM establishment.The convection exhibits a dipole distributive pattern between the SCS and Sumatra area before the SCSSM onset and the convection change shows an opposite trend between the SCS area and the south of Sumatra area.Before(during) the SCSSM sets up, the convection over the south of Sumatra area thrives (weakens).Therefore,we can regard the beginning date of the time period when the T_BB difference between the SCS and the south of Sumatra area≤5K and maintains for one pentad as an index of the SCSSM onset.

Key words:Sumatra;convection;Asia-Australian ";land bridge";;Indo-China Peninsula;SCS summer monsoon