The spatial and temporal variability of convective instability in the south of Western Siberia during the summer months of 1990–2019 was analyzed using Total Totals index values computed from ERA5 (ECMWF) data. For a 30-year period and specific decades, the spatial variability of the mean Total Totals values calculated for high atmospheric instability (by values above the 75th percentile) has been estimated. Centers with maximum values of the Total Totals index were localized for the 6, 9, and 12 UTC that approximately correspond to the beginning, maximum, and end of active convection under intra-mass conditions. The intra-decadal variability of the atmospheric convective potential was evaluated based on the Total Totals index over Western Siberia. Under changing climate conditions, the areas with the greatest changes in convective potential were identified.
The spatial distribution of the thunderstorm activity was obtained for the territory of Western Siberia. In the paper three characteristics are considered. They are density of lightning discharges to the ground, the average number of days with a thunderstorm and the average duration of thunderstorms in hours. The observations of the network of 52 weather station and satellite information on the number of lightning discharges are used for the mapping thunderstorm activity characteristics. The obtained maps are qualitatively compared with each other and with the results of other studies.
The peculiarities of the development of strong convection in the atmosphere of Western Siberia, Gorny Altay and the Far East were studied on grounds of some characteristics. First of all, it is dynamics of parameters describing temperature stratification of the atmosphere up to the height of 5 km. The integrated characteristics, which, in addition to temperature stratification, include the estimation of humidity of different atmospheric layers, make up the second group. The third group of characteristics is indices evaluating the energy of convective potential of atmosphere. The forth group comprises indices describing vertical and horizontal flows in the atmosphere. The threshold values of some indices at which the thunderstorms are formed are defined.
The article presents a forecast of dangerous convective phenomena using one of the indices of instability (Total Totals index). The index values were calculated by Semi-Lagrangian Absolute Vorticity Numerical weather prediction (SL-AV NWP) model for the south of Western Siberia on 13 July 2014. The simulation result was compared with the Total Totals index values retrieved from product MOD07_L2 of spectroradiometer MODIS (the space platform "Terra"). Synoptic conditions and dangerous weather phenomena weather report for the selected date are also given in this study.
Data on temperature inversions in the vicinity of Tomsk on the basis of MTP-5PE profiler data carried out at the IMCES SB RAS were summarized. It is shown that during persistent long-lived powerful anticyclones there is high recurrence of temperature inversions - they occur every day, or 90% of the time. A few characteristics of inversions observed in the region of the Bogashevo airport are presented.
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