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Seasonal average distribution of mesoscale anomalies of the Black Sea surface temperature (SST) and features of their localization for various seasons are considered. The area of cold SST anomalies is detected in open western and central parts of the sea. It is shown that an autumn season makes a major contribution to the formation of long-lived mesoscale cold anomalies in the central parts of the sea. The key features are reproduced and the main physical mechanism of rapid development of a cold anomaly is determined in the numerical experiment using the WRF-ARW model with the attached 3dPWP unit. It is shown that fast cooling occurs mainly due to the entrainment of cold waters from a thermocline, which results in the abrupt deepening of the upper quasi-homogeneous layer. [ABSTRACT FROM AUTHOR]

Several algorithms have been proposed to retrieve near-surface wind fields from C-band synthetic aperture radar (SAR) images acquired over the ocean. They mainly differ in the way they retrieve the wind direction. Conventionally, the wind direction is taken from atmospheric models or is extracted from the linear features sometimes visible in SAR images. Recently, a new wind retrieval algorithm has been proposed, which also includes the Doppler shift induced by motions of the sea surface. In this article, we apply three wind retrieval algorithms, including the one using Doppler information, to three complex wind events encountered over the Black Sea and compare the SAR-derived wind fields with model wind fields calculated using the high-resolution weather research and forecasting (WRF) model. It is shown that the new algorithm is very efficient in resolving the 180° ambiguity in the wind direction, which is often a problem in the streak-based wind retrieval algorithms. However, the Doppler-based algorithm only yields good results for wind directions that have a significant component in the look direction of the SAR antenna. Furthermore, it is dependent on good separation of the contributions to the Doppler shift induced by surface currents and wind-related effects (wind drift and wind-sea components of the ocean wave spectrum). We conclude that an optimum wind retrieval algorithm should consist of a combination of the algorithms based on linear features and Doppler information. [ABSTRACT FROM AUTHOR]

The development of a severe bora during the winter period near the South Coast of Crimea has been reproduced using the regional atmospheric circulation numerical model. Characteristic features of the velocity and temperature fields responsible for the formation of an intense surface current above the lee slope of a mountain range, such as internal wave breaking and air-flow blocking, have been considered. The evolution of the thermodynamic field during the severe bora development and damping, which is accompanied by a sharp decrease in the air-flow temperature, the formation of a surface jet stream, and a considerable spatial-time variability in a wide scale range, has been considered. [ABSTRACT FROM AUTHOR]