Eddy Deformation and Kinetic Energy Conversion During the Eddy‐Kuroshio Interaction East of Taiwan. Issue 1 (21st January 2023)

• Record Type: Journal Article
• Authors: Wang, Ru; Liu, Ze; Li, Haiyan; Yin, Yuqi; Hou, Yijun
• Is Part Of: Journal of geophysical research. Volume 128:Issue 1(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-21
• Subjects: Oceanography -- Periodicals; 551.4605
• DOI: 10.1029/2022JC018616
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Eddy‐mean flow interactions have always been of interest to researchers because they are among the causes of energy cascades. Different from most previous studies, this research concentrates on the Kuroshio Current's effect on an eddy during multiple independent elliptical eddy‐Kuroshio interactions. Eddy deformation during the eddy‐Kuroshio interaction is applied as the statistical criterion to select the typical eddies that interact with the Kuroshio east of Taiwan. There are 9 anticyclonic eddies (AEs) and 15 cyclonic eddies (CEs) that satisfy the criteria from the 1993 to 2018 satellite altimeter data. The blocking effect caused by the anti‐phase velocity at the contact interface of the CE and Kuroshio results in the eddy kinetic energy (EKE) at the CE edge being obviously inhomogeneous, while the AE does not result in the same effect. Moreover, the temporal variation in EKE during the eddy‐Kuroshio interaction precedes the AE/CE deformation by approximately 0.55/0.27 interaction cycles. The Kuroshio has different modulation mechanisms for different eddy polarities. Barotropic and baroclinic instabilities contribute to the generation of EKE, with barotropic instabilities providing more than 10 times as much as baroclinic instabilities for the AE and 4 times as much for the CE. The advection effect of the AE on the Kuroshio is in anti‐phase with the effect of the Kuroshio on the AE, which eventually makes the AE shrink. They are in phase for the CE and lead the CE to eventually become meandering. Plain Language Summary: From the plane perspective, an eddy can be regarded as an ellipse, which reflects its anisotropic characteristics. During eddy‐Kuroshio interaction, if the eddy best‐fit elliptic eccentricity temporal variation has a monotonic trend, then this eddy is selected as a typical eddy, and the interaction between a typical eddy and the Kuroshio is defined as a typical event. We mainly focus on the kinetic energy variation and deformation of typical eddies that interact with the Kuroshio. In this process, eddy kinetic energy (EKE) variation precedes eddy deformation. When an anticyclonic eddy interacts with the Kuroshio, EKE is mainly generated by barotropic instability. When a cyclonic eddy interacts with the Kuroshio, EKE is generated by both barotropic and baroclinic instability. The distribution of EKE at the cyclonic eddy edge is uneven, which is due to the blocking effect of the Kuroshio caused by the cyclonic eddy. The difference in the polarity of the advection effect between the Kuroshio and different eddies results in different eddy evolution processes. The anticyclonic eddy gradually shrinks until it disappears, while the cyclonic eddy becomes meandering with its opening toward the Kuroshio. Key Points: Individual typical eddies that interact with the Kuroshio are selected by using elliptical eddy deformation with the Mann‐Kendall test Cyclonic eddy: uneven distribution of eddy kinetic energy (EKE) at the edge; EKE is caused by barotropic and baroclinic instability; it turns into a meandering Anticyclonic eddy: even distribution of EKE at the edge; EKE is mainly caused by barotropic instability; it shrinks and disappears