摘要
利用NCEP/NCAR逐日再分析资料分析了南海夏季风与印度夏季风的爆发时间,根据爆发时间差值区分了差异大小年,结果表明二者的爆发具有明显的年际异常。差异偏小年,南海夏季风爆发时,印度半岛已经盛行偏西风,两者几乎同时建立;而差异偏大年,南海夏季风爆发后7候左右印度才盛行偏西风,印度夏季风爆发得晚,环流形势有明显差异;进一步分析机制表明,印度夏季风的建立主要由经向温度反转所决定,而南海夏季风的建立取决于纬向温度反转,二者的爆发具有相对独立性,且纬向温度反转的早晚更大程度上影响了差异的大小,积温线密集带出现的早晚决定了温度反转的早晚。
Based on the NCEP/NCAR daily reanalysis data, the onset dates of the South China Sea summer monsoon (SCSSM) and Indian summer monsoon (ISM) are investigated, in such a way that the great and small difference years are defined by using the difference of the two onset dates. Results show that the difference has obvious interannual variations. In the small difference years, when the SCSSM bursts, the westerly has prevailed over Indian Peninsula, and therefore the two summer monsoons burst almost synchroneously. However in the great difference years, the ISM bursts ( i. e. the westerly is prevailing over Indian Peninsula) in about the seveth pentad after the onset of the SCSSM, so the onset of the ISM is much later than that of the SCSSM. The analysis on mechanisms of monsoon onset shows that ISM onset is mainly related with the turning of meridional temperature gradient, while SCSSM onset is associated with the turning of zonal temperature gradient;the two onset dates are relatively independent from each other. The zonal temperature gradient turning is more important for the differences of the two onset dates. The two temperature gradient turnings depend on the appearance of the intensive belt of accumulated temperature contours.
出处
《南京气象学院学报》
CSCD
北大核心
2009年第1期64-70,共7页
Journal of Nanjing Institute of Meteorology
基金
江苏省气象灾害重点实验室开放课题
关键词
南海夏季风
印度夏季风
爆发
年际差异
独立性
South China Sea summer monsoon
Indian summer monsoon
monsoon onset date
interannual variation
meridional temperature gradient
zonal temperature gradient