On the Possibility of Forecasting Abrupt Differences in Average Daily Air Temperature (a Case Study of Irkutsk)

Abstract

This paper presents the technique for forecasting abrupt warmings and coolings during a month, based on the model developed in the Department of Meteorology and Climatology of Saratov State University. The model is built upon the principle of “floating analog” as suggested by V.F. Martazinova on the basis of the quasi-bimonthly rhythmicity of atmospheric processes substantiated by her. The Euclidean distance formula was used to determine the most typical situations in which there occur abrupt warmings and abrupt coolings. Such situations are referred to as reference situations, and when making a forecast, they serve as predictors. The identification correctness of reference fields is confirmed by synoptic analysis. It was found that winter coolings in Southern Siberia are governed by two types of processes: a radiation cooling in the central region of the winter Asian anticyclone, and advection of cold air masses along the eastern periphery of the winter Asian anticyclone. The warmings in the winter in the south of Siberia are associated with warm advection across the southern part of an extensive depression adjacent to the northern periphery of the region of high pressure located further to the south. The correctness of dates of differences in average daily air temperature according to an independent sample made up 71% for heat waves, and 69% for cold waves. Such a correctness can be considered highly successful in view of the rather rigid criterion of wave correctness and the monthly forecast lead time.