Impact of Submesoscale Eddies on the Transport of Suspended Matter in the Coastal Zone of Crimea Based on Drone, Satellite, and In Situ Measurement Data

Abstract

High-resolution measurements by unmanned aerial vehicles (UAVs), satellite and in-situ data are used to study the optical structure of coastal submesoscale eddies and their influence on the transport of total suspended matter (TSM). It is shown that submesoscale cyclones cause intense cross-shelf TSM fluxes and its subsequent accumulation in their cores, similar to what is observed in large mesoscale anticyclones. UAV measurements make it possible to observe intensive dynamic processes on the periphery of eddies, seen as a periodic structure with scales of 20–100 m; the spiral structure of TSM transport; and convergence of TSM in the cores of cyclones. Using UAV guidance, detailed measurements of the distribution of hydrological and hydro-optical characteristics of one of these eddies, with a diameter of about 2 km, were obtained during a scientific cruise in October 2019. Warm brackish water with a high TSM content and the descent of all isosurfaces were observed in the core of this cyclone, located near the topographic slope. We suggest that the probable reason for the convergence in such submesoscale cyclones is the interaction of radial currents with the topographic slope, which causes downwelling in the coastal part of eddies.