热带东风急流的演变特征及其与亚非降水的关系

The Evolution and Influence of the Tropical Easterly Jet and it’s Effect on the Regional Precipitation

为初步了解热带东风急流与亚非降水尤其中国东部、华南地区天气系统之间的关系,利用NCEP/NCAR月平均再分析资料,结合全球综合分析降水集(CMAP)及Ni o3.4海温指数,采用突变检验、小波分析、相关分析、合成分析等方法,对TEJ的结构、演变特征及其与亚非地区降水和大气环流的关系等进行研究。分析表明:TEJ从南海上空向西延伸,经印度到达非洲北部上空,中心位于印度半岛南端、阿拉伯海上空。利用"区域平均"法,定义了热带东风急流指数(TEJI),讨论了该指数62年的年际、年代际变化特征,并分析了TEJI与亚非降水、大气环流及ENSO的关系,结果表明:TEJ呈现强度一致减弱趋势,且突变大致发生在1978年;小波分析表明标准化TEJI存在准10年振荡周期;主要降水带出现在急流入口区右侧和出口区左侧,降水主要位于南亚和东亚季风区内;亚非季风区夏季降水与TEJ响应最敏感的区域是西亚、北非(负相关)、南亚(正相关);海平面气压场和南亚高压与TEJ密切相关,对中国东部和华南地区的旱涝预报起着重要的作用。

In order to interpret the association between the Tropical Easterly Jet and the precipitation in Africa and A- sia, especially the weather system of South China, the Mutation, Wavelet Analysis, Correlation Analysis and Com- posite Analysis are used in this paper to study the structure, evolution and the relationship between the Asian and African regional precipitation, General Circulation and TEJ by using the NCEP/NCAR reanalysis monthly mean data from 1948--2009, the CMAP divided by NOAA climate prediction center, and the Ni？ o3.4 ST Index from 1950 2009. The analysis shows：TEJ extends from the South China to the Northern Africa through India Peninsula. Its core is located at Southern India Peninsula over the Arabian Sea. We use the method of Zone Leveling to define the Tropical Easterly Jet Index（TEJI）, discussing the interannual and interdecadal variations of the TEJI during 62 years, and analysis the relationship between the index and precipitation of the Asian and African, General Circulation , the results show that： The TEJ overall showing consistent signs of abating, while the climate jump appeared in1978; The Wavelet Analysis of the time series of standardized indices shows： there exists a prospective 10-year cy- cle. The main precipitation area appears in the right of entrance and right of exit of TEJI, precipitation mainly locat- ed in the South-Asia monsoon region and the East-Asia monsoon region and the largest correlation of the area is West Asia, North Africa（Negative Correlation）, South-Asia（Positive Correlation）. Other, Correlation Analysis and Com- posite analysis between the TEJI and the Atmospheric Circulation, Sea-Level Pressure field and South Asia High are closely related to the TEJ, and it plays an important role in Drought and Flood forecasting of China especially in the East and South China.