Observation and Lagrangian Analysis of Quasi‐Stationary Kamchatka Trench Eddies

Abstract

AbstractBased on satellite altimeter data for the last 25 years, an area over the Kuril‐Kamchatka Trench (KKT) was found near the southern tip of Kamchatka Peninsula where mesoscale anticyclonic eddies have stalled for a long period of time. Using altimetry‐based Lagrangian maps, we detected 24 quasi‐stationary Kamchatka trench eddies (KTEs). Their genesis is related to anticyclonic eddies generated in the Kamchatka bays. After reaching the western slope of the KKT, those eddies slowdown and stagnate there. During the stagnation phase, all the KTEs were found to merger with anticyclonic eddies advected from the north. This feed up was accompanied by a significant increase of the KTEs in size and eventually by their destabilization. By arranging the data in Hovmöller diagrams, we got spatial patterns of the variability in the eddy kinetic energy and vorticity in the altimetry era. The typical eddy in this family KTE2017 has stagnated in the catching area during 8 months and was sampled in September 2017 in a cruise. The conductivity, temperature, pressure (CTD) measurements and Argo T/S vertical profiles demonstrated a typical subarctic vertical structure of water masses in summer. Different kinds of Lagrangian indicators were computed to study the life cycle of KTE2017. The KTE2017 during the stagnation phase of its life was found to be a shielded anticyclonic vortex surrounded by smaller‐scale cyclones. This configuration maintained its stability and stagnation over the KKT. We discuss different reasons by which KTE2017 and other KTEs have stagnated in the catching area.