Vertical structure anomalies of oceanic eddies in the Kuroshio Extension region

Abstract

Using collocated altimetry sea surface height anomalies (SSHA) and Argo profiles within detected eddies, we investigated structures of temperature, salinity, potential density, geostrophic current, mixed layer depth (MLD), potential vorticity (PV), and buoyancy frequency (N) in the Kuroshio Extension (KE) region under the influences of oceanic eddies. We identified 54,302 oceanic eddies (snapshots) in the KE region during the period of 1999-2013. The composite analysis showed that changes in physical parameters modulated by the climatological composite eddies (hereinafter referred as composite eddies) were mainly confined in the upper 800 m. At the eddy core, the maximum cooling in the composite cyclonic eddy (CE) reaches 2.00°C at ∼360 m, with maximum salinity change of −0.13 psu at ∼260 m and maximum potential density change of +0.27 kg/m3 at ∼310 m. In contrast, the maximum warming in the composite anticyclonic eddy (AE) reaches 1.78°C at ∼410 m of the eddy core, with maximum salinity change of 0.12 psu at ∼260 m and maximum potential density change of −0.22 kg/m3 at ∼410 m. There were obvious anti-clockwise and clockwise geostrophic current anomalies associated with the composite CE and AE, respectively. The seasonal mean eddy-modulated MLD anomaly had significant seasonal variations. Besides, they could modulate opposite PV changes, the magnitude of which varied with depth. This article is protected by copyright. All rights reserved.