The results of the Laboratory of Nonlinear Dynamical Systems (2020)

 

Calculation and analysis of daily Lagrangian maps in the altimetric velocity field over the past 25 years have made it possible to find an area near the southern tip of Kamchatka, where mesoscale anticyclonic eddies moving from the north regularly stagnate over the Kuril-Kamchatka trench for many months. With the help of such maps, 24 stationary eddies were identified and studied in 1993-2019. It is shown that they are “genetically” related to eddies generated behind capes in Kamchatka bays and then migrating southward with the current. In this case, the stationary vortex is an accumulator of merging vortices. A typical eddy stagnated over the trench for 8 months and was investigated during the cruise of the R/V Akademik Oparin in September 2017. CTD-survey showed a typical vertical structure with a warm surface layer, cold and freshened subsurface layer and a warm intermediate layer of water trapped in the core. Using Lagrangian maps of various indicators, the life cycle of this eddy from birth to decay was analyzed and it was found that this anticyclone was screened by smaller cyclones along its periphery. This configuration kept it stable and stagnant over the trench for a long time. The analysis of various factors and mechanisms supporting the stagnation of the Kamchatka eddies above the trnch and their subsequent decay has been carried out.