Seasonal Variability of Temperature Fronts in the Black Sea from Satellite Data

The structure and seasonal variability of temperature frontal zones and fronts in the Black Sea are studied on the basis of a modern high-resolution satellite data set. The distributions of the total temperature gradient allow us to distinguish the following frontal zones: the western frontal zone; the Turkish coastal frontal zone; the Anatolian upwelling frontal zone; the southeastern coastal frontal zone; northeastern, Crimea, and Kerch-Feodosia frontal zones; and the frontal zone of the deep part of the Black Sea. Large-scale fronts are identified within most frontal zones based on an analysis of distributions of meridional and zonal temperature gradients. It is shown that the combined effect of large-scale processes (seasonal warming and cooling of waters and their advection by the Rim Current) and regional factors (river discharge, coastline configuration, shelf width, development of upwelling, and formation of coastal eddies) produces significant spatiotemporal variability of the temperature field and, hence, frontal zones and fronts. It is ascertained that most fronts exist for several months. In the northern part of the sea, the fronts intensify mainly in winter due to an increase in the contrasts between warm Rim Current waters and colder coastal waters. The frontal zones near the southern coast of the sea intensify mainly in late spring–summer during the spring flood, the development of Anatolian upwelling, and active warming of waters in the eastern part of the sea.