南海夏季风维持期的气候特征Ⅱ——年代际变化  

CLIMATOLOGICAL CHARACTERISTICS OF THE MAINTAINING PERIOD OF SOUTH CHINA SEA SUMMER MONSOON Ⅱ——Interdecadal Variation

作　　者：冯瑞权[1] 王安宇[1] 唐天毅[2] 李国丽[1] 林建恒[2] 梁建茵[3] 吴池胜[1] 樊琦[1] 

机构地区：[1]中山大学大气科学系季风与环境研究中心,广东广州510275 [2]澳门地球物理暨气象局 [3]中国气象局广州热带海洋气象研究所,广东广州510080

出　　处：《热带气象学报》2005年第2期123-130,共8页Journal of Tropical Meteorology

基　　金：中国科学院知识创新工程项目(ZKCX-2-SW-210)资助

摘　　要：利用NCEP1958～1997年逐日格点气象资料对我国南海地区(105～120°E,5～20°N)夏季风维持期的年代际变化进行了仔细分析,分析结果发现对南海地区夏季风影响最大的是1970年代末期大气环流的突变。突变以1978年为界,分析工作主要是将前20年情况与后20年进行对比。前20年夏季风建立晚、结束早、降水较少、对流活动较弱、季风较弱;后20年则与此相反,季风建立早、结束晚、降水较多、对流活动较强、季风较强。分析对比前20年与后20年夏季风维持期高低空环流形势后发现,后20年南海地区上空对流下层辐合较强而对流层上层辐散较强,显然这种形势对后20年南海夏季风和对流降水的发展是十分有利的。需指出的是南海地区中心部分夏季风维持期的降水和OLR值的年代际变化趋势正好与南海其它地区相反,也就是说后20年南海地区中心部分降水较少,OLR值较高,而前20年正好相反。后20年和前20年的ENSO指数和南海地区海温的差别也十分明显,前20年ENSO指数和海温较低,而后20年都较高。Using daily gridpoint meteorological data of NCEP from 1958 to 1997, interdecadal variations of the summer monsoon in the South China Sea region (105～120°E, 5～20°N) are comprehensively analyzed for both active and inactive periods. The results show that the abrupt change in the general circulation in the late-1970’s is the strongest factor affecting the summer monsoon in the region. As the abrupt change occurred in 1978, comparisons are made between the 20-year period before it and that after it. For the first 20-year period, the summer monsoon had later onset and earlier ending, less precipitation and weaker convection than the late one. In the upper troposphere the divergence of wind field is more strong in the second 20-year periods than that in the first period above SCS, and on the contrary in the lower troposphere the convergence of wind field is more strong in the second 20-year period than that in the first period above SCS. Obviously this situation is favorable to the development of summer monsoon and convective precipitation above SCS for the second 20-year period. The interdecadal variation trends of precipitation and OLR in both periods over the central South China Sea and just the opposite from the whole region. In other words, precipitation is less but OLR is higher in the central part in the second 20-year period than in the first one and the whole region. The differences in the ENSO index and the South China Sea SST are also large between the two periods. They are higher in the first period.

关 键 词：南海地区 维持期 气候变化 

分 类 号：P425.42[天文地球—大气科学及气象学]