Characteristics of thunderstorm centers during the development of mesoscale convective systems over the south of Western Siberia

In this work, estimates of thunderstorm activity during the passage of mesoscale convective complexes (MCC) in the south of Western Siberia for 2016–2019 were obtained. When analyzing the trajectories of the MCC movement, it was revealed that it passes from the southwest to the northeast. The duration of the thunderstorm activity generated by the MCC is on average about 9 hours. At the same time, the duration of thunderstorm activity less than 4 hours was not noted. average area of a thunderstorm center ~ 5700 km2. The average distance covered by a thunderstorm is ~ 470 km. According to WWLLN, the number of lightning strikes is ~ 530

Analysis of spatio-temporal variability of lightning activity and wildfires in Western Siberia during 2016-2021

This research compares the spatial and temporal variability of lightning activity associated with wildfires in several natural geographical zones ofWestern Siberia from 2016–2021. The study was based on the World Wide Lightning Location Network (WWLLN) and The Fire Information for Resource Management System (FIRMS) for the warm (April–October) season. It was revealed that areas of hotspots and lightning activity most often coincide in the southwestern part of the territory (near Khanty-Mansiysk and Tyumen), in the mountain regions (Kuznetsk Alatau, Altai), and in the northern part of Kazakhstan. Maximum values of lightning occur in July for the whole territory of Western Siberia, and maximum values of hotspots occur in April in the central and southern regions of Western Siberia. Despite the largest number of fires in the south of the territory, the probability of ignition from lightning over the whole warm season is higher in the northern parts ofWestern Siberia; it reaches up to 30%. Thus, the revealed lightning–fire association allows us to better understand this process in the region that will be useful in the prediction of the potential fire danger in different natural zones

Gas dynamics of stationary supersonic gas jets with inert particles exhausting into a medium with low pressure

Issues related to the development of tools for mathematical modeling of stationary supersonic flows of an ideal compressible gas with inert particles are considered. A mathematical model is constructed that describes the flow of an inviscid compressible gas with inert particles in a jet flowing from an axisymmetric nozzle into a flooded space. Provided that the flow is supersonic along one of the spatial coordinates, the Euler equations are hyperbolic along this coordinate. For numerical calculations of the gas flow field, the finite volume method and the marching method are used. For integration over the marching direction, the three-step Runge–Kutta scheme is used. The procedure for calculating the flows includes the reconstruction of the values of the desired functions on the faces of the control volumes from the average values over the control volumes and the solution of the problem of the decay of an arbitrary discontinuity (the Riemann problem). The Lagrangian method of test particles is used to describe the dispersed phase. The effects of the reverse influence of particles on the flow of the carrier gas are not taken into account. The effects of viscosity and rarefaction of the gas flow are taken into account only when the gas interacts with particles. Calculation of the trajectories of inert particles is carried out in a known flow field of the carrier gas. The motion trajectories of discrete inclusions in jet flows with strong underexpansion are presented. The influence of the particle size and the coordinates of the particle entry point into the flow on the features of their transfer by the jet stream are discussed. Efficient means of numerical simulation of stationary supersonic flows of an ideal compressible gas with particles in nozzles and jets have been developed. The calculation results are of interest for studying supersonic gas suspension flows around bodies and for calculating oblique shock waves

ERA5 reanalysis for the data interpretation on polarization laser sensing of high-level clouds

Interpreting the results of a high-level clouds (HLCs) lidar study requires a comparison with the vertical profiles of meteorological quantities. There are no regular radiosonde measurements of vertical profiles of meteorological quantities in Tomsk. The nearest aerological stations are several hundred kilometers away from the lidar and perform radiosonde measurements only a few times a day, whereas lidar experiments are performed continuously throughout the day. To estimate meteorological conditions at the HLC altitudes, we propose to use the ERA5 reanalysis. Its reliability was tested by comparing with the data from five aerological stations within a radius of 500 km around Tomsk. A labeled database of the lidar, radiosonde, and ERA5 data (2016–2020) for isobaric levels 1000–50 hPa was created. The temperature reconstruction error over the entire altitude range was characterized by an RMSE of 0.8–2.8 ◦C, bias of 0–0.9, and Corr ~1. The accuracy of the relative vertical profiles (RMSE 25–40%, Bias 10–22%, and Corr <0.7) and specific humidity (RMSE 0.2–1.2 g/kg, Bias ~0 g/kg, and Corr ~0) at the HLC altitudes were unsatisfying. The ERA5 data on wind direction and speed for the HLC altitudes were promising

Analysis of the embedded convection of frontal cloud systems based on satellite and ground-based measurements

Based on satellite and ground-based measurements, the characteristics of the atmosphere during the passage of frontal cloud systems with embedded convection were evaluated. An approach was developed to identify centers of embedded convection in frontal cloud systems, which allows one to identify with high probability mesoscale phenomena in frontal clouds (in the horizontal and vertical planes). Based on the developed approaches and the obtained estimates of atmospheric characteristics, the methodology of automatic detection of the centers of embedded convection using satellite data will be implemented

Verification of GPM IMERG data on the total precipitation in Western Siberia in the warm season

This paper presents results of verification of recovered precipitation sums based on GPM IMERG microwave satellite measurements with standard observations at hydrometeorological stations in Western Siberia during summer period. The results revealed good agreement between GPM IMERG data and ground observations at the network of meteorological stations with a correlation coefficient of 0.987. The statistical analysis showed that the average discrepancy between daily precipitation sums according to GPM IMERG data and ground observations for all cases considered is 1.2 mm. The obtained accuracy of GPM IMERG data allows it to be used for most tasks

Smoke plumes from wildfires and the electrical state of the surface air layer

Using ground-based observation and satellite remote sensing data from 2006 to 2020 the smoke effect from distant wildfires in Siberia on the electrical state of the surface air layer is studied. The cases are considered where smoke covers the troposphere down to the surface layer and where smoke is observed only in the middle and upper troposphere. It is found that smoke from wildfires in these cases strongly but differently affects the electrical state of the surface air layer

The electric field of the undisturbed atmosphere in the south of Western Siberia: A case study on Tomsk

Currently, many researchers have an interest in the investigation of the electric field in the fair-weather electric environment along with its diurnal and seasonal variations across all regions of the world. However, a similar study in the southern part of Western Siberia has not yet been carried out. In this regard, the paper aims to estimate the mean values of the electric field and their variations in this area using the example of Tomsk. The time series of one-minute average potential gradient values as well as other quantities obtained from the geophysical observatory of the Institute of Monitoring of Climatic and Ecological Systems of the Siberian Branch of the Russian Academy of Sciences (IMCES SB RAS, Tomsk, Russia) from 2006 to 2020 is used in this study. The mean annual value of the potential gradient in Tomsk is 282 V/m and usually varies from 161 to 372 V/m. The diurnal variations in potential gradient per year on average are characterized by oscillations of the continental type with a double maximum and minimum. The main minimum of diurnal variations is 7 h and the main maximum is 21 h of local time (00 and 14 UTC, respectively). According to the annual mode, the maximum potential gradient is observed in February, and the minimum is recorded in June

Electric field of the undisturbed atmosphere in Tomsk

In the study, estimates of the variability of the surface electric field in undisturbed atmospheric conditions in Tomsk were obtained. It is noted, that the average and mode of the potential gradient in Tomsk under fair-weather conditions are ~280 and 250 V/m, and it is a typical range is 160–370 V/m. In the warm period of the year, the average and range of the potential gradient are 1.2 and 1.5 times, which less than in the cold period

Spatial and temporal variability of convective instability in the south of Western Siberia, determined on the basis of the Total Totals index (ERA5 reanalysis)

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