春季热带南大西洋海表温度异常与夏季亚澳季风区降水异常的联系

利用1979—2019年Hadley中心的海表温度资料、GPCP的降水资料以及NCEP-DOE的再分析资料等，分析了北半球春季热带南大西洋海表温度异常与北半球夏季亚澳季风区降水异常的联系。研究表明，北半球春季热带南大西洋海表温度异常与随后夏季热带西太平洋到南海（澳大利亚东侧海域到热带东印度洋）地区的降水异常为显著负相关（正相关）关系。北半球春季热带南大西洋的海表温度正异常可以引起热带大西洋和热带太平洋间的异常垂直环流，其中异常上升支（下沉支）位于热带大西洋（热带中太平洋）。热带中太平洋的异常下沉气流和低层辐散气流引起热带中西太平洋低层的异常东风，后者有利于热带中东太平洋海表温度出现负异常。通过Bjerknes正反馈机制，热带中东太平洋海表温度异常从北半球春季到夏季得到发展。热带中东太平洋海表温度负异常激发的Rossby波使得北半球夏季热带西太平洋低层出现一对异常反气旋。此时，850 hPa上热带西太平洋到海洋性大陆地区为显著的异常东风，有利于热带西太平洋到南海（澳大利亚东侧海域到热带东印度洋）地区出现异常的水汽辐散（辐合），导致该地区降水减少（增加）。

Relationship between spring South tropical Atlantic SST anomalies and summer precipitation anomalies in Asian-Australian monsoon region

Based on the sea surface temperature (SST) from Hadley Center, the precipitation data of GPCP, NCEP-DOE reanalysis data, the variability of boreal spring south tropical Atlantic (STA) SST anomaly (SSTA) and its association with boreal summer precipitation in the Asian-Australian monsoon region are investigated by using statistical analysis methods.The results indicate a significant negative (positive) relationship between boreal spring STA SSTA and subsequent summer precipitation anomalies in the tropical western Pacific-South China Sea (the sea between eastern Australia and the tropical eastern Indian Ocean).The spring positive STA SSTA can cause an anomalous vertical circulation over the equatorial Atlantic and tropical Pacific.The anomalous descending and low-level divergence over the tropical central Pacific can generate anomalous easterly conditions in the tropical western Pacific, which can result in a negative SSTA in the tropical central eastern Pacific.In the tropical central and eastern Pacific, the SSTA can be enhanced by the Bjerknes positive feedback mechanism from boreal spring to summer.During boreal summer, two anomalous anticyclones are induced over the western Pacific as a result of the Rossby wave response to the negative SSTA in the tropical central eastern Pacific.The tropical western Pacific and South China Sea (seas to eastern Australia and tropical eastern Indian Ocean) are experiencing anomalous easterly winds in 850 hPa, resulting in less (more) precipitation for tropical west Pacific and South China Sea.