On the Vertical Structure of Mesoscale Eddies in the Kuroshio‐Oyashio Extension

• Published in: Geophysical research letters 2023-12, Vol.50 (24), p.n/a
• Main Authors: Yao, H., Ma, C., Jing, Z., Zhang, Z.
• Format: Article
• Language: English
• Subjects: Aggregation; Baroclinic instability; Datasets; Eddies; Isopycnals; Marine ecosystems; Mesoscale eddies; Mesoscale phenomena; Ocean circulation; Structures; Swirling; Vertical profiles
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL105642

Vertical structure of mesoscale eddies is key to the eddy‐induced heat/material transport that further affects the climate and marine ecosystem. This study explores the vertical structure of mesoscale eddies in the Kuroshio‐Oyashio Extension region (KOE) and its underlying dynamics. By applying the hierarchical ascending classification to the observational and reanalysis data sets, we classify mesoscale eddies with three distinct kinds of vertical structures. Each kind of eddies exhibits clear spatial aggregation along a distinct zonal band. Eddies have core depths of 100–300 m in the northern part of the KOE and core depths of 300–500 m and 0–100 m in the southern. The eddy splitting or merging does not introduce new kind of eddy vertical structure but causes large intra‐kind variability. The different kinds of eddy vertical structures can be partially accounted for by the baroclinic instabilities at the eddy generation sites and local adjustment process. Plain Language Summary Mesoscale eddies are swirling motions with a radius ranging from several tens to a hundred of kilometers. The mesoscale eddies can cause strong vertical displacement of isopycnals, yet the vertical structure of such displacement has not been well understood. This study examines the vertical structures of mesoscale eddies in the Kuroshio‐Oyashio Extension region based on the observational and reanalysis data sets. Mesoscale eddies with three distinct kinds of vertical structures are identified. Both the eddy generation and local adjustment during eddy propagation play important roles in the vertical structures of eddies. Key Points Three vertical structures of mesoscale eddies are classified in the Kuroshio‐Oyashio Extension region Mesoscale eddy splitting or merging causes significant variation of vertical eddy structures Different vertical eddy structures can be partially accounted for by baroclinic instabilities and local adjustment process