To study the predictive properties of Weather Research & Forecasting and TSUNM3 mesoscale models for predicting heavy precipitation in Tomsk, a series of calculations were performed using these models for individual dates in 2021 and 2022, when the amount of precipitation accumulated over 12 hours exceeded 5 mm.

The paper examines the effect of temperature inversion on the level of air pollution. The Lagrangian stochastic dispersion model is used for calculations, which takes into account the initial rise of the impurity. It was found that for urban conditions with two point high-altitude sources (pipes), temperature inversion contributed to the increase in the amount of polluting particles in the studied area (respiration zone).

This study implements a one-way coupling between the mesoscale TSUNM3 model (1 km resolution) and the microscale M2UE model (0.5-10 m resolution) to analyze urban canyon aerodynamics and pollutant dispersion. The results demonstrate that simplified uniform velocity profiles lead to a 3-5% overestimation of pollutant concentrations due to decreased vortex flow intensity, while preserving the fundamental ventilation mechanism of the canyon.

The work presents the developed microscale model of turbulent air movement and the transfer of pas-sive gaseous pollutant in street canyons and city blocks. To parallelize this model, using the example of solving one transport equation, various parallel programming technologies were considered: MPI, OpenMP, OpenACC and CUDA. For each parallel implementation, the acceleration, efficiency and labor intensity of using the technology in question were assessed. Based on the results of computational experiments, the most suitable parallel programming technology -OpenMP for parallelizing the entire model was chosen. The results of using OpenMP in parallel imple-mentation of a microscale model of turbulent air movement and pollutant transfer are presented.

Relevance. The need to assess the stability of combustion, thermal stress and nitrogen oxides (NOx) emission during load reduction of a steam boiler. Since renewable energy sources and nuclear power plants will receive great attention in the future, coal-fired thermal power plants are to operate at reduced loads, so it is important to investigate the reliability of operation and environmental parameters of the boiler unit in case of load adjustment. Aim. To investigate pulverized coal fuel burnout, temperature parameters and NOx emission at 50 % reduction of boiler unit load in the base configuration and taking into account installation of tertiary blast nozzles. Objects. Furnace chamber of a natural circulation boiler unit with steam capacity of 220 t/h in the baseline layout and with tertiary air nozzles. Methods. The package of application programs FIRE-3D for numerical study was applied. Combustion of pulverized coal fuel is a complex physical and chemical process, therefore the interaction of gas flow and solid particles was modeled using Eulerian and Lagrangian schemes, respectively. In the gas phase, the combustion of volatiles and CO with further combustion of carbon residue are modeled. NOx emission is modeled using post-treatment models including formation of fast, fuel and thermal nitrogen oxides. Results. Temperature fields, flow characteristics, NOx emissions for different loads of the furnace chamber of the boiler unit with steam capacity of 220 t/hour are obtained on the basics of numerical modeling. The authors have obtained quantitative estimations of furnace environment parameters corresponding to several levels of boiler load reduction up to 50% of the nominal one. Installation of four tertiary blast nozzles allows reducing NOx emissions by 12.75% at theoretically required amount of air in burner devices (α=1.0).

For short-term forecasting of weather periods characterized by strong winds with gusts, it is proposed to use results of calculations based on the TSUNM3 (Tomsk State University Nonhydrostatic Mesoscale Meteorological Model) local weather numerical prediction model in combination with semiempirical formulas for estimating the scales of wind gust speeds. The comparison of the calculations and observations of meteorological parameters obtained for the conditions under consideration at the meteorological stations of the Atmosfera Common Use Center of the Institute of Atmospheric Optics, the AMMS-RF (airfield meteorological measuring system) of the Tomsk airport, and meteorological stations of the Tomsk CHEM showed the prospects of using the model for numerical forecasting of this dangerous weather phenomenon. The results of the work are to be used for the development of an information and predictive system for early warning of dangerous wind gusts.

Relevance. The need to analyze the furnace processes in boiler units with vertical vortex when arranging pulverized coal combustion with the enhancement of environmental parameters through the installation of tertiary blast nozzles. Despite the carbon-free policy in modern power engineering coal remains one of the main sources of energy, so the reconstruction of boiler units in order to reduce harmful emissions is very relevant. Aim. To study aerodynamics and combustion processes of pulverized coal fuel in the furnace chamber of a boiler unit with a tangential arrangement of burner devices using a combustion scheme with tertiary air blowing. Methods. The Eulerian–Lagrangian approach was applied to numerical study of flow characteristics, heat transfer and combustion in a furnace with a tangential burner arrangement. Also, k-ε model of gas turbulence, particle-turbulence interaction, diffusion model of particle dispersion, P-1 radiation modeling method and pulverized coal particle combustion model based on global particle kinetics and experimental data were used for numerical calculations. Results. Based on numerical calculations and analysis, the dependences of combustion product concentrations, temperature, hydrodynamics at combustion of Kuznetsky coal grade D in the furnace chamber with tangential arrangement of burners for brown coal, as well as at installation of tertiary blast nozzles have been obtained. Insufficient redistribution of air between burners and tertiary nozzles is revealed, as for maintenance of stable twist of vertical vortex and accordingly presence of high values of velocities at the outlet of burner devices it is not possible to increase the portion of tertiary air without reconstruction of burners. It is also established that the volume of the furnace chamber below the burners is poorly involved in heat exchange.

Доклад посвящен описанию технологии построения программного решения, автоматизирующего рутинные процессы, связанные с развитием оригинальных моделей TSUNM3 и CTM. Рассматриваемая прикладная научная информационно-вычислительная веб-система Метео+ предоставляет компьютерную поддержку научных исследований, в первую очередь, профессионалам в вычислительной геофизике, занимающимся разработкой и усовершенствованием собственных вычислительных моделей. При этом формируемая коллекция результатов моделирования позволяет привлекать уже других специалистов для детального анализа. The report is devoted to describing the technology of building a software solution that automates routine processes related to the development of the original TSUNM3 and CTM models. The considered applied scientific information-computational web-system Meteo+ provides computer support of scientific research, first of all, to professionals in computational geophysics who are engaged in development and improvement of their own computational models. At the same time, the formed collection of modeling results allows to involve already other specialists for detailed analysis.

A recurrent neural network model of long short-term memory (LSTM) type implemented to predict atmospheric air pollution by PM2.5 particles. Based on the distribution of meteorological values and concentrations of main air pollutants known from observations over the previous 6 hours, the task was set to predict PM2.5 concentrations for the next 3 hours. The total value of the average absolute error over the whole forecast was 2.35 μg/m3.

The influence of adverse weather conditions on air quality in Tomsk for certain dates in 2022 and 2023 was studied numerically using WRF and CAMx models. Calculated from hourly concentrations, the Common Air Quality Index is used to evaluate the level of air pollution. The numerical experiment was carried out on the implementation of measures to regulate emissions of business entities to improve the quality of atmospheric air in the city of Tomsk, depending on the declared regime of adverse weather conditions. It was found that in order to uniformly reduce the concentrations of the main pollutants of urban atmospheric air for the conditions under consideration, it is advisable to limit emissions from road traffic.

This work is devoted to the description and testing of the developed numerical microscale mathematical model of a non-isothermal turbulent flow and transport of a passive gaseous pollutant in street canyons and city blocks. The model is successfully applied to consider three-dimensional turbulent steady flows in a wind tunnel with a heated groove and in a cavern channel with a pollutant supply, for which measurements are available. A comparison of the calculated results, experimental data, and calculations obtained using ANSYS Fluent demonstrates the validity of the numerical model. The model is used to calculate and analyze the fields of wind speed and pollutant concentration, as well as the integral characteristics of the pollutant concentration in a street canyon as a whole and in a breathing zone (up to 2 meters above the canyon bottom) with partial or overall heating of the windward wall of the canyon. The flow structure and the observed maximum and average concentrations of the pollutants are found to depend significantly on the size of the heated part of the windward canyon wall.

The results of mathematical modeling of a nonisothermal turbulent air flow and admixture transport in an idealized street canyon are presented. The simulation is based on the RANS model, numerical algorithm, and application package developed by the authors, which are improved to take into account the effect of the buoyancy force on the aerodynamics and admixture transport. The mathematical model includes Reynolds-averaged stationary three-dimensional Navier–Stokes equations, as well as equations of heat transfer and impurity transport. For closing, a k-eps turbulence model is chosen taking into account the buoyancy forces. The numerical algorithm uses the finite volume method, nonuniform structured grids, and the fictitious domain method. The differential problem is approximated using Van Leer’s monotonized linear upwind scheme and piecewise linear interpolation for dependent quantities. The resulting grid equations are solved sequentially by N.I. Buleev’s iterative method. The SIMPLE algorithm is used to match the velocity and pressure fields. Using the developed package of applied programs, it is found that narrow and high street canyons are the least ventilated at a low wind velocity (~1 m/s), and the higher the street canyon with a constant width the higher the average concentration in the breathing zone. When studying the influence of the degree of heating of the surfaces of a street canyon with the same height and width, the least ventilated case is when the surface temperature of the windward vertical side of the canyon is 15–20°C higher than the ambient temperature. The main reason for this is the formation of a secondary vortex above the road surface, due to which the admixture is poorly carried out of the canyon.

Using the developed microscale mathematical model to study the distribution of vehicle emissions in street canyons, a study was made of the effect of footpaths raised or lowered by three meters relative to the roadway on the distribution of impurity concentration in the street canyon. The results showed that in both cases there is a multivortex turbulent movement of air masses, which worsens the process of weathering of pollutants from the street canyon.

A recurrent neural network model of the Long short-term memory (LSTM) type has been developed to predict atmospheric air pollution by PM2.5 particles. Based on the distribution of meteorological values and concentrations of the main atmospheric pollutants known from observations for the previous hours, the task of predicting the concentration of PM2.5 was set. The total mean absolute error for the entire forecast was 2,34 mu g/m(3).

This work is related to one of the methods of medical imaging - electrical impedance tomography (EIT). A feature of the considered two-dimensional mathematical formulation for the direct EIT problem is the use of an elliptic type equation with piecewise constant coefficients and a special integro-differential boundary condition at the contact boundary of the electrodes. For an approximate solution of the problem under consideration, a numerical method was developed using unstructured grids, the finite volume method for barycentric cells, and the Gaussian elimination method with the choice of the main element. The validation of the method was performed on a known analytical solution.

Представлены результаты расчетов метеорологических параметров и качества атмосферного воздуха во время аномально холодной погоды (T ниже - 20 оС) в г. Томск, полученные с помощью комплекса моделей WRF/CAMx. Результаты расчетов сравниваются с наблюдениями ультразвуковых метеостанций и температурных профилемеров ЦКП «Атмосфера», а также TOR-станции ИОА СО РАН. Для оценки уровня загрязнения атмосферы используется адаптированный Common Air Qiality Index (проект CiteairII, поддерживаемый ЕС), рассчитанный по ежечасным концентрациям.

The model of a multilayer perceptron has been developed and implemented to predict precipitation in a few hours based on the current state of meteorological parameters. The estimate of the model accuracy was 0.86, i.e. 86% of precipitation or no precipitation forecasts are predicted correctly.

Работа посвящена апробации разрабатываемой микромасштабной математической модели турбулентного течения и переноса пассивной газообразной примеси в уличных каньонах и городских кварталах. Апробация построенного численного метода выполнена на задачи моделирования ламинарного течения в канале. Верификация модели турбулентного течения и переноса примеси проведена на задаче обтекания прямоугольного препятствия и переноса примеси в идеализированном уличном каньоне.

A mathematical model and a numerical method for calculating meteorological parameters and quantities characterizing the quality of atmospheric air in the city, obtained using mesoscale models of numerical weather forecasting and impurity transport, are presented. The results of numerical calculations were compared with the data of observations performed with the instruments of the Central Collective Use Center "Atmosfera" of the Institute of Atmospheric Optics of the Siberian Branch of the Russian Academy of Sciences. The conducted studies have shown that the most unfavorable meteorological conditions leading to the accumulation of impurities near the earth's surface are observed in the morning and evening hours - this is a weak wind of variable direction and stable or neutral stratification of the surface air layer.

The work is devoted to approbation of the developed microscale mathematical model of turbulent flow and the transfer of passive gaseous admixture in street canyons and city blocks. Approbation of the constructed numerical method was carried out for the problem of modeling laminar flow in the channel. Verification of the model of turbulent flow and impurity transport was carried out on the problem of flow around a rectangular obstacle and impurity transport in an idealized street canyon.