Predictability of the Western North Pacific Subtropical High and Associated East Asian Monsoon Rainfall in APCC Multi-Models

Using selected models with better performance in simulating the Western North Pacific Subtropical High (WNPSH) variability can improve predictions for the East Asia Monsoon (EAM) precipitation. The selected model is clearly superior to the EAM rainfall prediction with the responses to sea surface temperature anomalies (SSTA) forcing and coupling in the atmospheric circulation between the East Asian subtropical Jet and WNPSH, which are similar to those in the observations. The findings of this study reveal that the "poor" model for EAM rainfall prediction is highly correlated with SSTA regardless of El Nino-Southern Oscillation phases. The "poor" model shows the responding circulation pattern to the El Nino persistent SSTA in the central-eastern Pacific until JJA, which induces more bias in the prediction of WNPSH variability and EAM rainfall. It is also noticeable that the "poor" model exhibits stronger barotropic response between the WNPSH and EASJ compared to observations, and therefore, it induces stronger relation between the EAJS and EAM rainfall. As a result, both atmospheric circulation itself over the EAM region and atmospheric-ocean interactions are important to enhance the predictability of the WNPSH and EAM rainfall.