2005年南海夏季风建立偏晚和持续异常偏南的成因分析  

REASONS FOR THE LATER ONSET OF SOUTH CHINA SEA SUMMER MONSOON (SCSM) AND ITS ANOMALOUS SOUTHWARD PERSISTENCE IN 2005

作　　者：鲍媛媛 琚建华[2] 金荣花 康志明 

机构地区：[1]国家气象中心,北京100081 [2]中国气象局培训中心,北京100081

出　　处：《热带气象学报》2009年第2期154-162,共9页Journal of Tropical Meteorology

基　　金：国家气象中心自筹基金;国家重点基础研究发展规划项目(2004CB418302)资助

摘　　要：通过分析大气环流及其热力结构演变特征,揭示2005年春末夏初南海季风爆发偏迟和持续异常偏南的原因。结果表明,阿拉伯高压偏强,与中高纬度高压脊叠加,导致较高纬度冷空气南下青藏高原南侧及中南半岛一带,抑制了中南半岛附近地区大气增温,不利于南海季风的爆发;索马里急流及赤道西风建立偏晚使中南半岛对流凝结潜热偏弱,是中南半岛一带大气增温偏迟的另一重要原因。6月上中旬,印度半岛北部冷空气势力偏强,大气增温缓慢,使印度季风和亚洲南部季风槽向北推进迟缓,使强劲的西南季风径直向东输送进入南海,有利于南海西南季风长期持续偏南。春末青藏高原积雪偏多,积雪融化抑制了地面增温和大气感热加热,是南海季风爆发偏晚的另一重要原因。6月上中旬,西南季风北上偏迟导致高原对流偏弱,热源偏弱,负反馈作用抑制了西南季风进一步北上,导致西南季风持续异常偏南。Atmospheric circulation and heat structures are discussed to reveal the reasons for the later onset of South China Sea Summer Monsoon（SCSSM） and its southward persistence in 2005. The results show that a stronger Arabian High and an overlapped ridge in the middle and high longitude guided colder air to India Peninsula and Bay of Bengal as well as the northern part of Indo-china Peninsula, which delayed the heating of the atmosphere and the outbreak of SCSSM. Somali Jet and cross-equatorial southerly winds in the Somalia region broke out later to weaken the convection and latent heating over Indo-china Peninsula, which is another important factor for the late onset of SCSSM. During the days before mid-June, strong cold air and slow heating of the atmosphere caused Indian Monsoon and its monsoonal trough to advance northward more slowly so that strong southwest monsoon moved eastward into the South China Sea, which was favorable for the southward persistence in South China. There were more snow over Tibet Plateau in late spring, the snow melting cooled down the surface atmosphere and led to weaker sensible heating, which played an important role in delaying the outbreak of the SCSSM. Southwest Monsoon staying in southern areas resulted in weaker convection and heating in the southern part of Tibet Plateau, and this kind of negative feedback led to the anomalously southward persistence.

关 键 词：西南季风 阿拉伯高压 热源 

分 类 号：P425.42[天文地球—大气科学及气象学] P434