Retrospective prediction in a coupled model over East Asia during El Nino decaying phase

The present work evaluates the simulations of rainfall responses over East Asia to the El Nino in a coupled model (FGOALS) and discusses the possible effect of El Nino on the East Asian rainfall during its decaying summer in terms of the seasonal forecast. The results show that the FGOALS model can reasonably simulate the El Nino related climate anomalies during the decaying summer, such as the negative sea surface temperature anomalies (SSTA) in the western North Pacific (WNP), the anomalous anticyclone over the WNP, and increasing rainfall over the middle and lower reaches of the Yangtze River. For 1 to 3 leading season forecast simulation, the model can roughly simulate the evolution of climate anomalies. However, the longer the predicting time is, the weaker the SSTA and anomalous anticyclone over the WNP are, which tends to cause the decreased rainfall over East Asia. The simulations reveal that the SSTA associated with El Nino can remain for about three seasons. This provides a solid basis for the rainfall forecast over East Asia. In addition, it is suggested that the error of simulated East Asian rainfall may be related to the departure of ENSO simulation due to model bias.