Journal Article

Observed Influences of Subpolar Front in the Japan/East Sea on Winter and Spring North Pacific Storm Track Activity

Yu, Peilong, Duan, Mingkeng, Chen, Shiyao, Zhang, Chao, Lin, Xiaopei, Wang, Huijun

2025

Overview

This study investigated the response of the North Pacific storm track (NPST) activity to the meridional shift of the Japan/East Sea subpolar front during the cold season using a statistical method called generalized equilibrium feedback analysis. Results showed that the NPST response exhibits a basin‐wide anomaly in winter but a north‐south dipole in spring. Synoptic eddy temperature variance budget was employed to explore possible mechanisms from the perspective of eddy available potential energy (EAPE) generation. In winter, the baroclinic conversion directly induced by baroclinicity changes drives EAPE generation, and then, the positive eddy feedback reinforces this EAPE generation, giving rise to an intensified NPST. In spring, poleward‐shifted baroclinicity drives a displaced EAPE generation, leading to the poleward displacement of NPST. The shifted baroclinicity is caused by a basin‐scale warm air temperature anomaly, which is coherent with the anticyclone anomaly induced by the divergence of synoptic eddy heat and vorticity fluxes. Plain Language Summary The Japan/East Sea (JES), located upstream of the North Pacific storm track (NPST), is a semi‐enclosed marginal sea of the North Pacific and contains a subpolar front (SPF) that can significantly influence the local and remote atmosphere. Previous efforts explored the atmospheric response to the basin‐scale sea surface temperature variability over the JES, but the influence of SPF there remains unclear. In this study, the impact of JES SPF position variation on downstream NPST during the cold season was investigated. The NPST response shows a basin‐wide anomaly in winter, but a north‐south dipole in spring. Possible mechanisms can be attributed to the eddy available potential energy (EAPE) generation by baroclinic conversion. In winter, the baroclinicity‐induced conversion drives the EAPE generation, which is further reinforced by the positive eddy feedback. In spring, poleward‐shifted EAPE generation is dominated by the displaced baroclinicity associated with a basin‐scale warm air temperature anomaly. Such warming is coherent with the anticyclone anomaly, which is formed by the synoptic eddy thermal and vorticity forcing. This study demonstrates a far‐reaching influence of the oceanic front in a marginal sea on the downstream storm track activity and large‐scale atmospheric circulation. Key Points The North Pacific storm track response to the meridional shift of Japan/East Sea subpolar front shows a basin‐wide (dipolar) anomaly in winter (spring) Winter response: Baroclinicity‐induced eddy potential energy generation, further amplified by eddy feedback Spring response: Poleward‐shifted eddy potential energy generation via dominant baroclinic conversion, driven by baroclinicity

• Publisher: John Wiley & Sons, Inc,Wiley
• Subject: Air temperature / Anticyclones / Atmospheric circulation / Baroclinic mode / baroclinicity / Baroclinity / Cold season / Cold storage / Dipoles / Displacement / Downstream / eddy available potential energy / Feedback / Influence / Japan/East Sea / Marginal seas / North Pacific storm track / Oceanic fronts / Potential energy / Sea surface temperature / Sea surface temperature variability / Seasonal variations / Spring / Spring (season) / Statistical methods / Storm tracks / Storms / subpolar front / Surface temperature / Temperature anomalies / Temperature variability / Vorticity / Warm air / Winter