南亚、东南亚地区大气环流季节突变的多年状况

在已有研究成果的基础上，本文利用FGGE-IIIb资料及欧洲中期天气预报中心（ECMWF）1980至1988年七层全球分析资料，分析了1979至1988年南亚、东南亚地区由冬至夏大气环流季节突变的状况。利用与这一地区主要天气系统密切相关的某些大气环流指标来描述该地区的季节突变，并根据这些指标的逐候演变、信噪比及候平均环流形势确定了突变发生的时段。在此基础上，本文讨论了季节突变的多年状况，用多年资料证实了南亚、东南亚地区由冬至夏季节演变过程存在着两次突变，分析了突变方式在区域间、高低层间及年际间的差异。

On the Abrupt Seasonal Change in the General Circulation over South and Southeast Asia Area

The FGGE-IIIb dataset and 1980-1988 ECMWF global analysis dataset have been used to ana-lyse the abrupt seasonal change (ASC) in the general circulation of the year 1979 to 1988 over the area of South and Southeast Asia.Some indices appropriately representing the charactetistics of the main synoptic systCms in the are as such as the South Asian high, Iran high, and southwesterly wind on 850 hPa have been used to des-cribe the ASC of the area. According to these indices, their information-noise rate and Pentad-mean circulation pattern, the Periods of each years ASC were determined. On the basis of above analyses, the inter-annual variation of ASC over the area was investigated, and the variation of the starting Pentad of ASC and its Period for different regions and different leve1s were studied.our results confirm the existence of the two stages of ASC over the area during the seasonal transi-tion of the general circulation from winter to summer. Furthermore, the wind field composites at 200 hPa and 850 hPa at the beginning and ending Pentad of each ASC have shown remarkable changes in general circulation over the area during the ASC.