Impact of Kuroshio Extension dipole mode variability on the North Pacific storm track

An index of a large-scale Kuroshio Extension (KE) sea surface height dipole (KED) mode is constructed using satellite altimeter sea level anomaly observations from January 1993 to December 2015 based on previous work of the second author. It is found that the KED mode that undergoes a decadal variation from a negative phase (a positive-over-negative dipole, KED−) to a positive phase (a negative-over-positive dipole, KED+) can affect the variability of the oceanic SST front and the North Pacific storm track. The results show that the oceanic SST fronts in the north of the KE region and in the KE region — referred to as the NSST and KSST fronts, respectively — are closely correlated with the KED mode. In the NSST front region, the SST front is stronger for KED− than for KED+, and the opposite is the case in the KSST region. It is further revealed that the decadal phase transition of the KED mode can change the location and strength of the North Pacific storm track, with the North Pacific storm track being slightly weaker and moving more northwards as a whole during the KED− mode than during the KED+ mode. The westerly wind associated with the storm track on the downstream side of the KE region intensifies and shifts northwards under KED− compared to KED+. Furthermore, the transition of the KED mode gives rise to changes in the North Pacific storm track by changing the NSST and KSST fronts and meridional heat flux