Geographical regularities of the permafrost-thermal regime of soils in Transbaikalia

Abstract

We have estimated the freezing-thermal regime of Transbaikalia soils qualitatively and quantitatively. Perennial permafrost almost throughout the region makes such an estimation of the thermal condition of the soils rather topical in terms of the region’s climatic resource. We have attempted to determine and classify thermo-freezing regime of the soils for entire Transbaikalia and show the general geographical characteristics of the thermal regime of winterly Transbaikalia. The studies of the 3.2-m thick soil layer were based on the perennial data of 49 meteorological stations. For the analysis of the thermo-freezing regime of the soils, we used the mean monthly values of the smallest temperature at the standard depth of the soil profile. The entire array of the temperature data was divided into five grades of different widths and represented in the form of vertical profiles. The steps of the scale reflect the progressing increase in winter cooling of the entire soil layer. The weakest soil cooling is observed for the eastern shore of Lake Baikal: these are the moderately cold conditions. In the southern closure of the Barguzin depression, the state of the soil thickness transits smoothly from moderately cold to cold conditions. Very cold soil conditions are propagating from southeast to northwest in the perennial permafrost zone. Severe conditions of soil are present in local regions of the southern part of the territory and its northern part where the sandy-loam soil with pebble admixture allows perennial permafrost to lie at small depths. Extreme severe conditions mainly occupy the races of total perennial permafrost.