The Interannual Variation of the South China Sea Summer Monsoon Trough and Its Impact

The South China Sea summer monsoon trough(SCSSMT) is an important part of the South China Sea summer monsoon system.It has distinct characteristics of interannual variation,which has important impacts on the summer circulation of China.In this paper,an intensity index of SCSSMT is brought forward first.Then strong and weak monsoon trough years are classified according to the index,and different variables of the background circulations associated with strong/weak monsoon trough years are synthesized.The synthesized results show that there exist quite different background fields,such as general atmospheric circulation,convective actions and SST in different monsoon trough years.It can be conferred that the monsoon trough anomaly,that is,anomalous strong/weak monsoon trough,is connected to the background fields.The impact of the monsoon trough anomaly on the precipitation of China is also discussed,which shows that anomalous South China Sea summer monsoon trough not only influences the precipitation in China,but also makes a remote impact on the circulation of the other areas in the Northern Hemisphere through teleconnection process.