Dynamical prediction of the East Asian winter monsoon by the NCEP Climate Forecast System

Abstract

The National Centers for Environmental Prediction (NCEP) Climate Forecast System (CFS) provides important source of information on seasonal climate prediction for many Asian countries that are affected by monsoon. In this study, the authors provide a comprehensive assessment of the prediction of East Asian winter monsoon (EAWM) by the CFS version 2 (CFSv2) using the hindcast for 1983–2010, with a focus on seasonal–interannual time scales. Output from the Atmospheric Model Intercomparison Project (AMIP) and the Coupled Model Intercomparison Project (CMIP) simulations is also analyzed to understand the physical process of monsoon. Several major features of the EAWM are well predicted by the CFSv2. Particularly, the EAWM‐related atmospheric circulation and surface climate over oceans are well predicted several months in advance, and the prediction over oceans is better than that over land. While the CFSv2 has low skill in predicting the Arctic Oscillation (AO), it well predicts El Niño‐Southern Oscillation (ENSO) and its impact on the EAWM, contributing to the decent prediction of EAWM. Comparisons among hindcast, AMIP, and CMIP indicate that ocean–atmosphere coupling is important for EAWM prediction. While the EAWM in AMIP is weaker, CMIP predicts more realistic monsoon features. The enhanced performance of CMIP is partly attributed to its better simulation of precipitation over the western Maritime Continent (MC). All three types of experiments fail to depict the relationship between EAWM and AO and simulate a stronger‐than‐observed response of EAWM to ENSO. Improving the simulation of convection over the MC potentially enhances the skill of CFSv2 in predicting the EAWM.