Long-term variability of sea surface temperature in the coastal zone of northeastern part of the black sea in spring and autumn

Within the frameworks of the presented model, the beginning of the spring and autumn hydrological seasons depends on the temperature regime of air flows in the region under investigation. As compared with the standard procedure of season determination, this model is more flexible in taking account of the probabilistic nature of the time of the beginning of hydrological seasons and variations of their duration. It ensures a higher reliability of estimates of thermal surface water properties and analysis of their evolution within the seasons and annual cycles. A considerable irregularity in the time of the beginning of spring and autumn seasons and a possibility of significant fluctuations of their duration changes the estimation of thermal surface water conditions so considerably that the initial (calendar) model can be no longer considered as the source of reliable information.