Analysis of dynamic variants of winter season structure and their climatic characteristicsin southwest of West Siberian Plain

Inthe general problem of research of climatic seasons we allocate an independent and significant aspect of studying their structure innatural, not calendar, borders. The problem can be solved by substantiation of zone structural models of seasonal rhythms, definition ofdynamic variants of structure for certain years, their climatic characteristics and modern tendency of development. The average longtermstructure of winter in natural zones of the investigated region is three-phased. It includes the following structural units: ''moderatelyfrosty phase'', (the first phase), ''significantly frosty phase'' (the second phase) and ''threshold of spring'' (the third phase). In certain yearsbecause of the circulating processes peculiarities we can observe some deviations in the structure of winter seasons from the zonemodel. By their structure deviations can be divided into the following types: ''three-phase'' winters, ''two-phase'' without the first or thethird phase, ''no-nuclear'', with ''unstable thermal regime'' and ''two-nuclear''. The data bank on natural climatic seasons of natural zonesof the southwest of the West Siberian Plain accumulated during 70 years (1936-2006) allowed us to carry out the spatial-temporalanalysis of winter rhythms peculiarities, and develop models of climatic regimes for the established types of season structure, which canvary essentially from type to type. The received data gave a chance to compare the climatic indicators of winter seasons calculated fortwo periods - 1936-1970 and 1971-2006 - and reveal the tendencies for changes of the given characteristics. The timing data ofdifferent types of structure of the winter season of the considered periods differ essentially. Nevertheless, the general feature for them islater dates of the beginning of the season in the second period, and earlier dates of the end of the season and its reduction regardless thetype of its structure. The data of the thermal regime also vary in the periods, though to a lesser extent, reflecting the tendency to thedecline of winter severity. Our research shows that the climate of the southwest of the West Siberian Plain has been warming since the1970s. The indicator is the winter season which is shorter and less severe. It is necessary to notice that works on studying the seasonalclimate rhythmics and their structural units in real, not calendar, borders are conducted rather rarely, which may be connected with thelabour-intensive character of required calculations. However, they give a chance to make a more objective idea about the majortendencies of development of natural processes and prospects for changes of natural conditions. It is very important not only from thetheoretical point of view, but also for various spheres of human life.

Keywords

Authors

References