This paper describes our experience in the application of Lagrangian mini-drifters in studies of coastal water circulation. As shown by our experiments in the Southeastern Baltic Sea, an application of Lagrangian mini-drifters makes it possible to detect the presence of complex sub-mesoscale vortex processes and inertial oscillations, i.e., processes that are difficult to numerically simulate. Moreover, the presence of vortex formations is able to keep passive objects (drifts, oil anthropogenic pollution and so on) floating in a strictly localized area for at least 1 week, even in changeable wind conditions. Special attention in the paper is paid to a performance comparison of the application of mini-drifters and an Acoustic Doppler Current Profiler (ADCP). The advantages of drifters for determining flow parameters at low speeds are noted. The main advantages of the proposed drifters are taken into account: the low cost of manufacturing drifters (∼ 150 USD per system) along with the low cost of GSM communications, the ease of manufacturing and operation, with no special technical experience required, and the link to obtaining operational data in real-time for up to several weeks make these systems valuable supplementary tools for remote sensing studies of processes in coastal zones.

Satellite radar (SAR) and visible band data from Envisat ASAR, ERS-2 SAR, Lansat-5,7,8 sensors were used to investigate internal waves (IWs) in the Black Sea. The three main areas of the Black Sea where surface manifestations of internal waves (SMIWs) were mostly observed are: the Danube Delta, Crimea Peninsula and the northeastern region near Novorossiysk. The main goal of our investigation was to define the mechanisms of IW generation in the non-tidal sea. In the first area, IWs are observed rather often due to surface intrusions of fresh waters of the Danube River. In contrast to usual soliton-like IW trains caused by river plumes, soliton trains near the Danuba Delta propagate in different directions and often subject to nonlinear interactions. The interrelation between location and orientation of IW trains and fresh water fronts is discussed. In the area off Crimea, in our opinion, IWs are generated mainly by upwelling relaxation and interaction between internal inertial waves and bottom topography features. SMIW in the northeastern part of the Black Sea are scarce, though IWs are regularly revealed by in-situ measurements.Field measurements were conducted in the northeastern part of the Black Sea from a small boat and from scientific sea platform near Crimea employing CTD probes, thermistor chain and Acoustic Doppler Current Profilers (ADCP). ADCP measurements allowed us to detect a number of IW trains. Their amplitudes were estimated to reach 5-8 m. Joint analysis of satellite SAR and subsatellite data gave an assessment of their typical wavelength at 90-100 m.

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The results of field experiments concurrent to satellite surveys conducted in the summer periods of 2014-2019 in the southeastern part of the Baltic Sea off Sambian Peninsula are presented. The main goal was to study coastal currents in a highly variable wind field and its impact on the transport of potential marine pollution. Southeast Baltic is, on the one hand, an area of active navigation, fishing, off-shore oil production, and, on the other hand, a rapidly developing recreation area. It is also an area of frequent massive blooming of harmful algae. Considering these facts, studying coastal currents and their impact on antropogenic and biogenic pollution propagation in the area is highly important. Our main research instrument was drifting Lagrangian buoys (mini-drifters) that are quite often used in oceanography today, Acoustic Doppler Current Profiler (ADCP) and CTD probe measuring temperature, conductivity (salinity) and pressure (depth) and in-situ turbidity and CHL-a In addition, we used satellite remote sensing data publicly available from European and American databases. Mainly, these were data obtained from Sentinel-2 (MSI), Landsat-8 (OLI/TIRS), Sentinel-3 (OLCI) and MODIS (Aqua/Terra) satellites. The experimental data allowed us to describe in detail the alongshore current structure and identify the areas most affected by marine pollution, among which are the most popular places of the region: the beaches of the Yantarniy settlement and Curonian Spit, a national nature reserve and a UNESCO World Heritage Site.