Estimates of the accuracy and rate of convergence of short-term meteorological forecasts using the regional climate model RegCM4

We use the regional climate model RegCM 4.9 for the territory of Southern Russia to estimate the accuracy of meteorological forecasts. The errors of meteorological and climatic forecasts is due to complex non-equilibrium physicochemical processes in the components of the Earth's geosystem, which are characterized by gasdynamic and thermal instabilities at various spatial scales. A method for assessing the convergence of forecasts based on time series analysis is discussed for various localities. The reliability of forecasts for temperatures up to 1 degree can lie within 5-10 days for the south of the European part of Russia, depending on the predominance of cyclonic or anticyclonic atmospheric movements. The interval of acceptable precipitation forecast, as a rule, does not exceed 2-4 days for an area of about 10 4 km 2 and greatly decreases with decreasing area of the region under consideration. The annual volume of precipitation correlates in the cities of Rostov-on-Don and Volgograd at the level of 70 percent with each other. The correlation between the Rostov-on-Don City or the Volgograd City on the one hand, and the cities Astrakhan, Stavropol, Elista on the other hand, turns out to be significantly less, ranging from 30 to 40 percent.