摘要
根据１９８０～１９９１年云顶黑体温度（ＴＢＢ）相位和强度的变化确定了南海夏季风爆发的时间，分析研究了夏季风爆发期间 ＴＢＢ场和 ８５０ ｈＰａ风场的变化过程及其与海温的关系。结果表明：南海夏季风爆发平均时间是５月第４候，它爆发的时间和强度有显著的年际变化，并与大气的低频振荡及前期海洋的热力状况有密切关系。南海夏季风爆发早年（４月第６候），副热带高压较弱，撤离南海较快，从赤道东印度洋到赤道西太平洋，大气对流活动较强，夏季风爆发南海早于盂加拉湾，季风爆发时９０～１００°Ｅ区域过赤道气流显著加强。夏季风爆发晚年（６月第１候）情况相反。南海夏季风爆发早晚与大气３０～６０天振荡到达南海的位相有关，前冬和早春南海海温的高低和４月中旬至５月中南半岛强对流区的出现时间，是南海夏季风爆发年际变化的前期征兆。根据前冬南海海温预测１９９８年南海夏季风爆发的时间和强度与实际相符。
The onset time of the South China Sea Summer Monsoon (SCSSM) is defined by the changes in phase and strength of temperatures of block body (TBB) at cloud top, and the process of change of TBB and wind field at 850 hPa, as well as its association with sea surface temperatures during SCSSM onset time is analysed. The main results are as follows. The mean onset time of SCSSM is the fourth pentad of May for the period of 1980 to 1991. There exists a significant interannual variation in the onset time and strength of SCSSM which is closely related to low-frequency oscillation of the atmosphere and the heat states of ocean before the SCSSM onset time. In the years of early onset of SCSSM (the sixth pentad of April) deep convective activities are observed over the region from the eastern equatorial indian ocean to the western equatorial Pacific ocean, in association with the fast eastwards retreat of the weak western Pacific subtropical high, and the onset time of summer monsoon is earlier over the South China Sea than over the Bay of Bengal. The stronger cross--equatorial flow over the 90- 100°E region during the onset time is observed, and vice versa in the years of late onset of SCSSM (the tirst pentad of June). The onset time of SCSSM is associated with the phase of 30- 60 day oscillation of atmosphere arriving over SCS. High or low SST of SCS during the prior winter and early spring and the time of the strongly convective weather occurrence over the Indo-China from middle of April to May are indicators of interannual variations of onset of SCSSM. Prediction of the onset of l998' SCSSM based on SST during the prior period in SCS is consistent with the fact.
出处
《大气科学》
CSCD
北大核心
2000年第6期785-794,共10页
Chinese Journal of Atmospheric Sciences
基金
中国科学院"九五"重大应用基础研究项目!KZ951-A1-203
国家自然科学基金!49875015
国家重点基础研究发展规划
关键词
夏季风爆发
对流活动
低频振荡
年际变化
大气
summer monsoon onset
convection activities
low-frequency oscillation, sea surface temperature
interannual variation
