A Lagrangian technique, based on computation of maps of specific indicators [1], is elaborated to document and study the life story of any mesoscale eddy in altimetric or numerically derived velocity fields. It allows us to visualize and analyse the main events in life cycle of ocean eddies: birth and formation, evolution, deformation, merger, splitting, erosion and decay. It is also shown how to identify origin of water masses inside eddies and to localize and date the events of entrainment and detrainment of water to and from the eddy [2]. We focus on mesoscale eddies distributed along the deep Japan, Kuril-Kamchatka and Aleutian trenches which are found to serve as a catching area for some Kuroshio rings, Hokkaido, Kuril, Kamchatka and Aleutian anticyclonic eddies. We identify those eddies which have a tendency to approach the trench and either remain quasi-stationary there or propagate along the trench axis even though the background flow has an opposite direction. By computing and inspecting altimetry-based daily Lagrangian maps from 1993 to the present time, we were able to identify all mesoscale trench eddies in the Northwest Pacific, to find the conditions for formation of specific eddies, to track their trajectories and monitor them from the birth to eventual decay.
1. S.V. Prants, M.Yu. Uleysky, M.V. Budyansky. Lagrangian oceanography: large-scale transport and mixing in the ocean. Berlin. Springer. 2017. 271 p.
2. S.V. Prants, M.V. Budyansky, M.Yu. Uleysky. J.Geophys.Res. V.123. P.2081 (2018).