Ice phenomena in the Black Sea and the Sea Of Azov and their forecasting under the conditions of climatic changes

Abstract

Ice cover is one of the most important factors determining the state of sea surface. Study and forecasting of its parameters is not only of scientific, but also of great practical interest for maritime economy. In the northern-west part of the Black sea and in the Sea of Azov the ice situation can be quite complicated, resulting in restriction of navigation opportunities and requiring use of icebreakers. Accounting actual and forecast ice characteristics significantly affects the efficiency of hydrometeorological services in marine industries, which determines the relevance of the chosen topic. Modern global climate change led to changes of specific parameters of the ice regime in the northern-west part of the Black Sea and the Sea of Azov. Studies showed that for the last 30 years the number of warm winters had increased by 15% and the number of cold winters had decreased by 19%. The duration of the ice period had decreased by a decade in the Sea of Azov and by a month in the northern-west part of the Black Sea. This determines the need for verification of the methods used for ice phenomena forecasting. Currently, hydrometeorological services are delivered using the methods of ice phenomena forecasting that were developed in the 1980s. The main disadvantage of these methods is the limitation of the period of their application and the fact that they do not consider any climatic changes taking place over recent years. The article's aim is to assess ice conditions changes in the north-western part of the Black Sea and in the Azov Sea over the past 20 years and to verify the method used for forecasting the dates of ice formation and disappearance. The analysis showed that during the studied period ice formation begins later and its disappearance is observed earlier than if compared with average multi-year periods. Verification of the ice formation and disappearance forecasting method showed unsatisfactory results that did not meet the practical requirements. Based on the regression analysis new modified equations for forecasting the dates of ice formation and disappearance were defined. The accuracy of a new equation-based calculation technique constitutes 70-94% and the forecasting equations can be recommended for practical use.