Evolution and Structure of the Kuroshio Extension Front in Spring 2019

Jiahao Wang,Kelan Zhu,Xi Chen,Kefeng Mao

doi:10.3390/jmse8070502

Jiahao Wang, Kelan Zhu + Show 2 more

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https://doi.org/10.3390/jmse8070502

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Abstract

Satellite data products and high-resolution in situ observations were combined to investigate the evolution and structure of the Kuroshio Extension Front in Spring 2019. The former reveals the variation of the front is influenced by the northward movement of the Kuroshio Extension through transporting warm and saline water to a cold and brackish water region. The latter indicates steep upward slopes of the isopycnals, tilting northward in the frontal zone, as well as several ~300 m thick blobs of North Pacific Intermediate Water between 26.25 and 26.75 kg/m3, where conspicuous thermohaline intrusions occur. Further analysis indicates these thermohaline intrusions prefer to alternate salt fingering and diffusive convection interfaces, and are affected by strong shears.

Highlights

The Kuroshio Extension (KE) is a variable eastward inertial jet separating from the coast of Japan near 35◦ N in the North Pacific Ocean [1,2,3]
Without the constraint of coastal boundaries, it is rich in large-amplitude meanders and energetic pinched-off eddies, which are often associated with the sharp subsurface front named the Kuroshio Extension Front (KEF) [2,3,4,5,6,7]
We investigated the KEF’s evolution and structure based on the high-resolution in situ observations from a Moving Vessel Profiler (MVP), a shipboard Acoustic Doppler Current Profiler (ADCP), and satellite measurements in Spring 2019

Summary

Introduction

The Kuroshio Extension (KE) is a variable eastward inertial jet separating from the coast of Japan near 35◦ N in the North Pacific Ocean [1,2,3]. The fine-scale structure named the thermohaline intrusion is often observed in the frontal zone and has an important role as the indicator of lateral exchange [13]. It is indicated by changes in the sign of vertical temperature or salinity gradients, and can be attributed to double diffusion, either by salt fingering or diffusive convection through heat/salt fluxes as well as advection through cross-front velocity perturbation [4,6,13,14,15,16,17,18,19,20]

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