关于东亚副热带季风若干问题的讨论  

Discussions on the East Asian subtropical monsoon.

作　　者：何金海[1] 赵平[2] 祝从文[2] 张人禾[2] 汤绪[3] 陈隆勋[2] 周秀骥[2] 

机构地区：[1]南京信息工程大学江苏省气象灾害重点实验室,南京210044 [2]中国气象科学研究院,北京100081 [3]上海市气象局,上海200030

出　　处：《气象学报》2008年第5期683-696,共14页Acta Meteorologica Sinica

基　　金：公益性行业(气象)科研专项项目(GYHY200706005);国家重点基础研究发展规划项目(2006CB403607)

摘　　要：利用NCEP/NCAR再分析格点资料、TRMM卫星降水资料、中国东部站点降水资料和CMAP降水资料,重点讨论了东亚副热带季风雨季的起始时间、建立特征及其和南海夏季风的关系,同时也讨论了东亚副热带季风的可能机制。结果表明:(1)东亚副热带季风雨季于3月底—4月初(第16—18候)在江南南部和华南北部首先开始,伴随着降水的开始是偏南风的增强和对流性降水的显著增加,华南前汛期开始。(2)东亚副热带季风雨季的建立早于热带季风雨季,在热带季风建立后两者的雨带、强西南风带、强垂直运动带、强低空水汽辐合带均是分离的,南海热带季风在其建立后,与东亚副热带季风发生相互作用,促使副热带季风雨带季节性北进,两者共同影响中国的旱涝。(3)3月中下旬,东亚大陆(包括青藏高原)上空大气由冷源转为热源,东亚大陆与西太平洋之间的纬向热力差异及其相应的温度和气压对比均发生反转。东亚大陆(包括青藏高原)的动力和热力作用究竟是否是东亚副热带季风雨带提前建立的机制值得进一步研究。文章最后讨论了有关东亚副热带季风的共识与分歧。Based on NCEP/NCAR gridded reanalysis, TRMM precipitation data, CMAP, and rainfall observations in East China, a study is conducted with focus on the timing and distinctive establishment of the rainy season of the East Asian subtropical monsoon （EASM） in relation to the South China Sea （SCS） tropical summer monsoon （SCSM）. A possible mechanism for the EASM is inves- tigated. The results suggest that （1） the EASM rainy season begins at first over the south of the Jiangnan region to the north of South China in late March to early April （i. e. , pentads 16 - 18）, and then the early flooding period in South China starts when southerly winds enhance and convective rainfall increases pronouncedly; （2） the establishment of the EASM rainy season is earlier than that of its counterpart, the SCSM. The EASM and the SCSM each is featured with its own independent rain belt, strong south- westerly wind, intense vertical motion, and robust low-level water vapor convergence. The SCSM interacts with the EASM, causing the EASM rainy belt to move northward. The two systems are responsible for the floods/droughts over the eastern China; and （3） in mid-late March, the eastern Asian landmass （especially the Tibetan Plateau） has its thermal condition changing from a cold to a heat source for the atmosphere. A reversal of the zonal thermal contrast and related temperature and pressure contrasts between the land- mass and the western Pacific happens. The argument about whether or not the dynamic and thermal effects of the landmass really act as a mechanism for the earlier establishment of the EASM rain belt is discussed and to be further clarified. Finally, the article presents some common understandings and disagreements regarding the EASM.

关 键 词：东亚 副热带季风 南海 热带季风 

分 类 号：P462.41[天文地球—大气科学及气象学]