东亚夏季风与澳洲冬季风强弱互补变化联系及其异常环流特征

利用NCEP/NCAR再分析资料、Hadley中心海温资料及CMAP降水资料等，通过亚澳季风联合指数挑选异常年份，对东亚夏季风和澳洲冬季风强度反相变化特征进行研究。结果表明，当东亚夏季风偏强、澳洲冬季风偏弱时，南北半球中低纬地区都出现了复杂的异常环流系统。在热带地区对流层低层，西北太平洋为异常反气旋式环流系统所控制，与南太平洋赤道辐合带的异常反气旋环流在赤道地区发生耦合，形成赤道异常东风，而在南北印度洋上则存在两个异常气旋式环流系统。在这两对异常环流之间的海洋性大陆地区，出现赤道以南为反气旋环流而赤道以北为气旋式环流。在东亚季风区，东南沿海的东侧海洋上存在反气旋异常，中国东南地区受异常反气旋西南侧的东南风影响。此外，澳洲北部受异常西风影响。这就形成了东亚夏季风偏强、澳洲冬季风偏弱的情形，从而东亚夏季风和澳洲冬季风活动出现了强弱互补的变化特征。当东亚夏季风偏弱、澳洲冬季风偏强时，南北半球的环流特征则出现与上述相反的环流特征。总体而言，当东亚夏季风偏强、澳洲冬季风偏弱时，东亚—澳洲季风区在南北半球呈现出不同的气候异常分布特征，即北半球降水北少南多、气温北高南低，南半球降水西多东少、气温西高东低。

Complementary relationship between East Asian summer monsoon and Australian winter monsoon and the related circulation anomalies

Complementary relationships between the East Asian summer monsoon and the Australian winter monsoon have a significant impact on the climate anomalies in the Northern and Southern Hemispheres.Using the National Centers for Environmental Prediction/National Center for Atmospheric Research(NCEP/NCAR) reanalysis data,the Hadley Centre Global Sea Surface Temperature dataset,and the CPC Merged Analysis of Precipitation (CMAP) data,based on the joint index of East Asian-Australian monsoon,this paper investigated the reverse variation characteristics of the East Asian summer monsoon and Australian winter monsoon intensities.Results show that when the East Asian summer monsoon is stronger and the Australian winter monsoon is weaker,complex anomalous circulation systems appear in the middle and low latitudes of the Northern and Southern Hemispheres.In the lower troposphere of the tropical region,the anomalous anticyclonic circulation system in the northwestern Pacific is intensified,which is coupled with the anomalous anticyclonic circulation in the South Pacific Convergence Zone(SPCZ),forming an anomalous easterlies near the equator,while there are two anomalous cyclonic circulation systems in the northern and southern Indian Ocean.In the marine continental area between the two pairs of anomalous circulations,the anticyclonic circulation is located in the south of the equator and the cyclonic circulation in the north of the equator.In the East Asian monsoon region,there is an anticyclone anomaly on the east side of the southeast coast of China,and southeastern China is affected by the southeast wind on the southwest side of the anomalous anticyclone.In addition,the northern Australia is affected by the anomalous westerly wind.As a result,the East Asian summer monsoon is stronger and the Australian winter monsoon is weaker,which leads to a complementary relationship between them.When the East Asian summer monsoon is weaker and the Australian winter monsoon is stronger,the circulation characteristics of the Northern and Southern Hemispheres are opposite to the above.On the whole,when the East Asian summer monsoon is stronger and the Australian winter monsoon is weaker,different climate anomaly distribution characteristics appear in the Northern and Southern Hemispheres of the East Asian-Australian monsoon area,that is,the precipitation is less in the north(east) but more in the south(west) and the temperature is higher in the north(west) and lower in the south(east) in the Northern(Southern) Hemisphere.