여름철 동아시아 및 북서태평양 몬순간의 장주기 변동성에 관한 연구

Abstract

A recent study suggested that the relationship between the East Asian summer monsoon (EASM) and the western North Pacific summer monsoon (WNPSM) has experienced a decadal change around 1993-1994. Based on a longer-term integration of a hybrid coupled model, the present study investigates decadal variations in the relationship between the EASM and the WNPSM. Apparent decadal variations in the above relationship have been identified in the model simulation. The authors have analyzed the spatial pattern and variability during strong and weak EASM-WNPSM correlation periods. The purpose of this study is to understand potential reasons for decadal variations in the relationship between above two sub-monsoons. It is found that the precipitation variability associated with the WNPSM (ENSO) is enhanced over the East Asia and western North Pacific regions during periods when the EASM-WNPSM relationship is strong (weak). The large variability in precipitation associated with the WNPSM during strong periods strengthens the Pacific-Japan like atmospheric teleconnection from the tropical western Pacific. In contrast, the Pacific-Japan like pattern is not significant during weak periods. On the other hand, the large ENSO amplitude during weak periods results in an enhanced precipitation variability associated with ENSO. The results suggest that ENSO can destructively interfere with the relationship between the EASM and the WNPSM.