Turbid and brackish Azov waters penetrating through the Kerch Strait significantly modify the biooptical and thermohaline features in NorthWestern part of the Black Sea. The Kerch Strait itself is another additional powerful source of suspended matter. Analysis of the high-resolution Landsat imagery and MODIS satellite data on the total suspended matter (TSM) concentration and sea surface temperature is carried out in the present work to study the Kerch waters propagation in the Black Sea. It is shown that Kerch waters most frequently propagate westward from the strait in the form of a narrow jet having a width of 1-10 km. Turbid waters are mainly observed in shallow areas do not crossing isobaths of 20 meters. In winter such jets are observed in both optical (turbid) and infrared measurements (cold water). On average, they stretch from the Kerch Strait to Cape Meganom and cover the whole Feodosia Bay. Strong northeast storms increase the outflow of the Azov waters from the strait and intensify the western propagation of Azov waters. The propagation area and distance from the source of waters with high TSM are related to the strength and duration of storms. During southern storms, vast areas with large turbidity, which are not related to the penetration of Kerch waters, are observed in the vicinity of the Kerch Strait along the shores of the Kerch and Taman Peninsulas. Such increase of turbidity is a result of wave action, that lead to the coast erosion and resuspension of bottom sediments near the clay cliffs. High values of TSM are mostly observed up to the isobath of 50 meters. In some cases, Kerch waters can be transported offshore on the large distances upon the action of mesoscale eddies advection.

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This paper reports the results of field experiments performed at an offshore oceanographic platform in the Black Sea during spring and fall seasons 2005-2011. Observations of the air-sea interaction were made using direct and remote sensing methods in the coastal zone where the interaction is complex and still poorly understood. A specialized research platform, managed by the Marine Hydrophysical Institute (MHI), is placed on the shelf slope approximately 600 m offshore the Crimea coast, Ukraine. The water depth at the site is about 30 m. The experiment program included conventional turbulence measurements with the eddy-covariance method as well as remote radio-polarimetric measurements with a newly developed instrument. The study was concentrated on the air-sea interaction during episodes of weak wind in the atmosphere and upwelling events in the ocean. Analysis of the collected data confirmed significant dependence of the surface drag coefficient on the air-sea temperature difference under weak wind conditions. However, this analysis also demonstrated a new air-sea interaction regime, which is characterized by large quasi-periodic (periods about 3.5 h) turbulence oscillations developing initially in the atmosphere and later (after about 10-12 h) in the sub-surface water layer. The analysis of radiopolarimetric measurements provided the characteristics of the gravity-capillary wave field during these events.

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Quasi-periodic features of the inter-annual and inter-decadal spatial-temporal variability of the wind speed absolute value (W) in the Black Sea area are assessed based on a series of 60-100-year-long direct observations performed at eight coastal stations, and also on the reanalysis data obtained from the NDP-048, WDC, NCDC, NCEP/NCAR (1948) and MERRA (1980-2015 arrays. Three groups of oscillations with the periods T about 60-90, 20-40 and 3-15 years that present in the W direct data are shown by means of the wavelet analysis. As for long-period oscillations (Т ~ 60-90 years), possible relations of such quasi-periodicity with the phases of the North Atlantic Oscillation index characterizing the atmospheric circulation features are investigated. Calculated according to the MERRA array reanalysis, the mean anomalies of January -February average W series separately for groups of years with the values of the NAO index > +1 and <-1 demonstrated in their dynamics the values of different signs for the same Black Sea areas. It is revealed that during the periods when the index positive phase is mainly predominant, the W positive anomaly is formed over the southwestern, south-eastern and eastern parts of the sea adjacent to the coast at a distance 20-100 km from it, and the W negative anomaly -over the rest of the sea. During the years when the index phase is mainly negative, the signs of the W anomalies over almost the same regions change to the opposite ones. IntroductionClimate variability study and prediction are among the most important tasks of Earth sciences being of high applied significance [1,2]. To diagnose and predict the Black Sea condition, the parameters of the wind regime are used, since the tangential wind stress directly affects the sea waves, circulation and mixing of water and indirectly -the thermal and water balance.Main results of wind research in the Black Sea area are presented in [3,4]. They showed the presence of significant negative linear trends in the series of mean annual wind speeds and the frequency of storms in the 20 th century. In [4] it was noted that since the beginning of the 2000s, there was a tendency to increase the frequency of storm winds practically at all hydrometeorological stations. However, the study of the cyclicity of these processes was almost neglected.Search and study of the wind regularities in the inter-annual variability and their relations with the quasi-periodicity of macro-circulation processes in the atmosphere have been still insufficiently developed [5,6]. Therefore, the research of long-term trends in variation of the wind conditions is one of the most important practical tasks in studying the wind field variability in the Black Sea area.