Response of the North Pacific Storm Track Activity in the Cold Season to Multi-scale Oceanic Variations of Kuroshio Extension System: A Statistical Assessment

In this paper, a statistical method called Generalized Equilibrium Feedback Analysis (GEFA) is used to investigate the responses of the North Pacific Storm Track (NPST) in the cold season to the multi-scale oceanic variations of the Kuroshio Extension (KE) system, including its large-scale variation, oceanic front meridional shift, and mesoscale eddy activity. Results show that in the cold season from the lower to the upper troposphere, the KE large-scale variation significantly weakens the storm track activity over the central North Pacific south of 30°N. The northward shift of the KE front significantly strengthens the storm track activity over the western and central North Pacific south of 40°N, resulting in a southward shift of the NPST. In contrast, the NPST response to KE mesoscale eddy activity is not so significant and relatively shallow, which only shows some significant positive signals near the dateline in the lower and middle troposphere. Furthermore, it is found that baroclinicity and baroclinic energy conversion play an important role in the formation of the NPST response to the KE multi-scale oceanic variations.