南海夏季风爆发与西北太平洋热带气旋活动

Relationship Between the South China Sea Summer Monsoon Onset and the Tropical Cyclone Activity in the Western North Pacific

利用1965—2007年美国台风预警中心(JTWC)的热带气旋(TC)及NCEP/NCAR再分析资料,初步研究南海夏季风爆发与西北太平洋(包括南海)热带气旋活动之间的关系。结果表明,南海夏季风的爆发伴随着西北太平洋(尤其南海区域)TC生成个数和活动频数比爆发前有显著增加,而超过1/2的年份南海夏季风爆发前2候和爆发候西北太平洋(150°E以西)有TC活动,表明TC活动可能是南海夏季风爆发的触发机制之一。在大多数(77%)南海夏季风爆发偏早年,爆发前2候和爆发候西北太平洋TC活动偏多,且TC生成位置偏西;而大多数(77%)爆发偏晚年份,爆发前2候和爆发候没有TC活动。季风的偏早爆发受季节内振荡、西北太平洋TC活动、中纬度冷空气活动等复杂因素影响,而季风的偏晚爆发则主要受季节内振荡影响。

The relationships between the South China Sea summer monsoon onset（SCS SM） and the tropical cyclone（TC） activity in the western North Pacific（WNP）,including the South China Sea,are preliminarily investigated,by using the Joint Typhoon Warning Center（JTWC） TC data and the National Center for Environmental Prediction / National Center for Atmospheric Research（NCEP/NCAR） daily mean reanalysis data.Results show that the genesis number and the occurrence frequency of TC over the WNP（especially the SCS） increase evidently associated with the SCS SM onset.More than a half years TC occur over the WNP（west of 150 E） during 1-2 pentads and the onset pentad before the SCS SM onset,implying a precursor for SCS SM onset prediction.In most of the early onset years（77%）,more TC occur during the 1-2 pentads and the onset pentad and TC geneses mostly occur in the WNP.However,in most of the late onset years（77%）,no TC occur during 1-2 pentads and the onset pentad.The early summer monsoon onset may be affected by complex factors including the intraseasonal oscillation,the TC activity in the WNP,and the cold air activity in middle latitude,while the late monsoon onset is mainly affected by the intraseasonal oscillation.