Seasonal change in anomalous WNPSH associated with the strong East Asian summer monsoon

Abstract

The most striking features observed in the strong East Asian summer monsoon (EASM) are the seasonal change in the anomalous western North Pacific subtropical high (WNPSH) and the accompanying convective activities over the tropical Pacific and the Indian Ocean. The seasonal change in the anomalous WNPSH associated with the strong EASM has been studied through model experiments. The results of numerical experiments indicate that the anomalous WNPSH associated with the strong EASM has a strong seasonality with respect to its intensity and location. This is due to the difference between the contributions of the remote and local sea surface temperature forcings in the tropical Pacific and the Indian Ocean. It is also found that the air-sea interactions over the tropical western Pacific and the Indian Ocean are essential to appropriately simulate the intensity and location of the anomalous WNPSH, which in turn modulate the East Asian summer monsoon rainfall during the summer of the strong EASM years.