The Variability Of Kuroshio Extension And Its Connection With Storm Track In North Pacific

the variability of the Kuroshio extension (KE) jet is investigated by18years ofsea surface height (SSH) data from satellite altimeters. It is found that the KE jet canexhibit a decadal transition between widened (double) and narrowed (single) jets.Such a jet variability is a result of the interaction among the low-frequency wave(low-frequency SSH dipole mode referred to as a KE dipole mode hereafter),high-frequency eddies and mean flow, which is closely related to the phase andstrength of the KE dipole mode forced by the eddy forcing due to the nonlinearhighfrequency eddy interaction in the KE region.Moreover, the large-scale air-sea interaction also have an impact on thevariability of Kuroshio Extension. Thus, the relationship between the mesoscale eddykinetic energy (EKE) in the Kuroshio Extension (KE) region and North Pacificatmospheric storm track is investigated by introducing the EKE area index and usingthe regression analysis. It is found that the stronger North Pacific storm track isassociated with intensified Kuroshio Extension mesoscale eddy activity. The NorthPacific storm track shifts northward (southward) as the maximum EKE core in the KEregion is shifted to the north (south). However, there is an opposite variation betweenthe EKE and North Pacific storm track in zonal position. Moreover, it is shown thatthere is a lead–lag correlation between the EKE and North Pacific storm trackvariations. The strength of the EKE exhibits a3-4year lag positive (negative)correlation with the EOF1and EOF3(EOF2) of the North Pacific storm track, whilethe opposite is true for the position of the EKE. This can arise from the westwardpropagation of the sea surface height anomalies driven by AtmosphericTeleconnection Patterns associated with the North Pacific storm track.