Ground icing in the Tomsk region (Western Siberia)

Based on the analysis of meteorological observations on the territory of the Tomsk region in the last 20 years, new climatic characteristics of the spatio-temporal changes in ground icing (GI) have been obtained. Information is provided on the intensity of the types of deposits (large diameter, weight), the duration of the growth phase and, in general, a phenomenon that is important for the transport and energy industries. The revealed meteorological and synoptic conditions for the formation of various types of ground icing are necessary both for a more confident diagnosis and for improving the methods for predicting them. A large variation in the frequency of occurrence of GI is observed across the territory - ten or more times, and over the years - from two to seven times. The smallest number of GI is noted in the southeastern part, most often occur in the northern part of the region, which is extremely inaccessible for transport. In recent years, the rate of change in the repeatability of types GI has different signs: grained rime (GR) - slightly increases at most stations, glaze (G) - decreases; crystal rime (CR) also decreases. The recurrence of all types of GI in Tomsk has been declining. The non-stop duration of glaze and grained rime in most cases does not exceed one day, crystal rime, moist snow (MS) and icecrusted ground (ICG) - two days. The maximum duration of ice-crusted ground is ten days, for other types of GI - up to two days. The intensity of G and MS most often does not exceed 16 mm, a maximum of 44 mm; GR and CR - respectively, does not exceed 4 mm with a maximum of up to 9 mm. The occurrence of GI was observed both in cyclonic and anticyclone baric fields: in the first, GI and MS prevail, and secondly, CR and GR. GI in 77,3% of cases were observed in homogeneous air, 22,7% - on atmospheric fronts. The homogeneous air mass GI (especially CR) most often occur in anticyclones at the maximum developmental stage, or in low-gradient anticyclone fields, but there are cases in decaying or regenerating anticyclones. G was rarely observed in the rear parts of cyclones and low-gradient cyclonic fields, and MS in an anticyclone. The GR and MS often occur during the passage of warm, and G - cold sections of the Arctic fronts. CR was predominantly in homogeneous air mass. It is necessary to note the insufficient number of observation stations for the phenomena for high-quality service of the regional economic complex, especially taking into account the development strategy of the oil and gas industry and its road, pipeline and electricity supply. The emergence of intramass GI could not have been detected by such a rare network of hydrometeorological stations. We think that the results of the research can be used in various applications to clarify the climatic characteristics of GI, as well as in predicting the effects of ground icing.

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