Interdecadal Change in the Relationship between the Winter North Pacific Storm Track and the East Asian Winter Monsoon

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AbstractBased on the daily NCEP reanalysis, the present study investigates the interdecadal change in the relationship between the winter North Pacific storm track (WNPST) and the East Asian winter monsoon (EAWM), and evaluates the WNPST–EAWM relationship in 17 CMIP6 models. The results show that the out-of-phase WNPST–EAWM relationship underwent an interdecadal change in the mid-1980s. The WNPST–EAWM relationship became less significant during period 2 (P2; 1990–2015). The atmospheric circulation anomaly related to the EAWM during period 1 (P1; 1955–80) is more robust than that during P2. The interdecadal weakening WNPST–EAWM relationship may be attributed to the interdecadal damping WNPST–EAWM interaction. The EAWM-related anomalous baroclinic energy conversion and moisture effects, including meridional and vertical eddy moisture fluxes, contribute to the significant attenuation of the WNPST during P1. The transient eddy-induced dynamic forcing and thermal forcing anomalies, as well as the barotropic process represented by the local Eliassen–Palm flux divergence associated with WNPST, can also significantly manipulate the upper-tropospheric jet during P1. However, the atmospheric circulation and interaction between the WNPST and EAWM during P2 are not as significant as those during P1. The effect of ENSO on the WNPST is significantly different before and after the mid-1980s. After the mid-1980s, the WNPST shows the characteristic of moving equatorward during El Niño events. It seems that ENSO takes over the WNPST from the EAWM after the mid-1980s. In addition, except for BCC-ESM1, CanESM5, and SAM0-UNICON, most of the CMIP6 models cannot reproduce the significant out-of-phase WNPST–EAWM relationship.