Ivan Kovalets

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Jayjit Majumdar

University of Kalyani

Sophie Clayton

University of Washington

David Seamon

Kansas State University

Armando Marques-Guedes

UNL - New University of Lisbon

Mustafa Aydin

Kadir Has University

Mikail F Lumentut

National Taiwan University

Emre Erşen

Marmara University

Hossein Sadegh Lafmejani

Università degli Studi di Parma (Italy)

Sergey Konovalov

Russian Academy of Sciences 1

Luis Troccoli

Universidad de Oriente, Venezuela

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Papers by Ivan Kovalets

Radionuclides deposition on sea surface following hypothetical accidental releases at Korean nuclear power plant

Stochastic Environmental Research and Risk Assessment, Dec 30, 2023

Modeling of Radioactive Contamination of the Black Sea and Its Impact on Humans Due to Hypothetical Heavy Accident at the Zaporizhzhia NPP

Lecture notes in networks and systems, 2023

Long-Term Contamination of the Arabian Gulf as a Result of Hypothetical Nuclear Power Plant Accidents

Journal of Marine Science and Engineering

Long-term consequences of radionuclide contamination of the Arabian Gulf as a result of hypotheti... more Long-term consequences of radionuclide contamination of the Arabian Gulf as a result of hypothetical accidents at the Bushehr and Barakah nuclear power plants (NPPs) were studied using a chain of models including the atmospheric dispersion model RIMPUFF, the marine compartment model POSEIDON-R, and the dose model. The compartment model POSEIDON-R is complemented by a dynamic model of the biota food chain that includes both pelagic and benthic organisms. The source terms for the hypothetical releases of the selected radionuclides (134Cs, 137Cs, 106Ru, and 90Sr) in the atmosphere were defined as a fraction of respective reactor inventories available in the literature. Conservative meteorological scenarios for the calculation of the initial depositions of radionuclides were selected. Because the Gulf is shallow, a significant portion of the reactive radionuclides (134Cs, 137Cs, 106Ru) remain in the bottom sediments and continue to contaminate water and benthic organisms for a long peri...

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Determination of the parameters for the calculation of dry and wet deposition of chemicals in the Povitrya system

Mathematical machines and systems

The previously developed system Povitrya allows the calculation of the atmospheric distribu-tion ... more The previously developed system Povitrya allows the calculation of the atmospheric distribu-tion of 36 chemicals using the CALPUFF atmospheric dispersion model. In this paper, after the literature review and according to the requirements of the CALPUFF model, the values of the parameters for the calculation of dry and wet depositions of pollutants in the Povitrya system have been defined. Based on the analysis of the model parameters, the parameters that depend on the type of substance have been identified. For pollutants that spread in the form of aerosols, only one parameter – the scavenging coefficient included in the formula for the calculation of wet deposition – depends on the type of substance. Other deposition parameters for aerosols are a function of the characteristics of the particle size distribution, so they are not considered in this paper. The scavenging coefficient is specified for all types of chemicals – aerosols and gas-es modeled by the Povitrya system depending ...

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Geo-information web-system for presenting the results of the inventory of air pollution emis-sions in Kyiv

Mathematical machines and systems

In the current work, there has been developed for the first time a geo-information web-system for... more In the current work, there has been developed for the first time a geo-information web-system for presenting the results of the inventory of air pollution emissions in Kyiv from industrial en-terprises on the basis of the processing of data from the State Statistics Service of Ukraine, as well as estimates of geo-distributed emission fields from vehicles. The system contains infor-mation on emissions of 21 pollutants, including those that are regularly monitored in Kyiv by governmental agencies. The system is available via the link http://env.kiev.ua:8080/pollutionsystem/ pollutionsystem.html. Its main features – viewing on the map the locations of industrial emission sources for the selected substance, and the corre-sponding amount of emissions – can be used even by unregistered users. The developed system can be used in combination with the existing public and state systems for monitoring of air pol-lution in Kyiv for preliminary (screening) analysis of possible causes of high lev...

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Forest Wildfire at Chernobyl Nuclear Power Plant in June, 2018: Lessons Learned from Coupling of Stationary and Mobile Monitoring with Predictive Modeling of Atmospheric Radioactivity During the Event and Follow-Up Intercomparison of the Modeling Tools

AGU Fall Meeting Abstracts, Dec 1, 2019

Сравнение методик расчета параметров испарения опасных жидкостей с поверхности бассейна разлива на твердую поверхность

Математические машины и системы, 2017

Ensemble Data Assimilation of Concentration Measurements Following the Accidental Release of a Contaminant in the Ocean: Method Testing in an Idealized Setting

Pure and Applied Geophysics, 2022

The capabilities of the ensemble Kalman filter (EKF) data assimilation (DA) method to reduce erro... more The capabilities of the ensemble Kalman filter (EKF) data assimilation (DA) method to reduce errors in simulations of concentration distributions following the accidental release of a contaminant in the ocean were evaluated. The method was tested in an idealized setting where the contaminant was released in the ocean described by a simple linear Stommel model that includes the main features of two-dimensional (2D) wind-driven circulation in the ocean on the β-plane. The wind stress curl in the right-hand side of the equation for stream function was randomly perturbed to generate an ensemble of the perturbed fields of currents. The velocity fields obtained from the ensemble of stream functions were then used for the calculation of the ensemble of concentration fields following short-duration point release. On day 1000 of the simulation, correlation coefficients of the members of the concentration ensemble and the unperturbed concentration distribution fell to 0.087. The ensemble member with the maximum deviation from the unperturbed concentration distribution was selected to be used as “truth” in data assimilation experiments. Due to the high inhomogeneity of the concentration fields, the free regularization parameter had to be defined and tuned using the L-curve approach. Different DA scenarios were considered with different topologies of measurement networks and different source locations. In all cases, data assimilation gradually brought ensemble-averaged concentration fields close to the true distribution. The root mean square errors of the analyzed concentrations on day 1000 decreased by the factors varying from 3 to 4 in different DA scenarios as compared to the simulation without DA.

Ассимиляция данных в трехмерной модели распространения радионуклидов в водоемах тритокс системы Родос

The data assimilation procedure is developed for the 3D model of the radionuclide dispersion in w... more The data assimilation procedure is developed for the 3D model of the radionuclide dispersion in water systems THREETOX included into the Hydrological Disperision Module of the EC decision support system for offsite nuclear emergency management RODOS. The method is verified on the basis of the monitoring data on radioactive contamination of the Black Sea, and also on the simulated data of the radionuclide dispersion in the Kakhovka Resrvoir for the scenario of hypothetical accidental atmospheric fallout from the Zaporizhke NPP.

Flood forecasting and flood inundation mapping system developed for Ukrainian parts of Prut and Siret river basins within EAST AVERT project

Prut and Siret rivers are two neighbouring rivers the upper parts of which are located in south-w... more Prut and Siret rivers are two neighbouring rivers the upper parts of which are located in south-western Ukraine on the eastern slopes of the Carpathian Mountains. The upper reaches of Prut are located in Ivano-Frankivsk and Chernivtsi oblast of Ukraine, while the middle and lower reaches of Prut river flow along the border between Moldova and Romania. Most of the Siret river basin is located in Romania and only a small portion of its upper part – in Chernivtsi oblast of Ukraine. Within EC funded project EAST AVERT “Prevention and flood protection in Siret and Prut river basins through the implementation of a modern monitoring system with automatic stations” in addition to the strengthening of the monitoring system in the basins there were plans for modernization of the flood forecasting system in all three countries of these transboundary basins, as well as the simulation of flood inundation zones.

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Використання системи wrf-україна для прогнозування агрометеорологічних умов

Web-система прогнозування метеорологічних умов для довільної території на детальних сітках

Адаптация метеорологической модели WRF для прогнозирования полей ветра вокруг Ривненской АЭС

Mesoscale WRF meteorological model, adapted to provide a system of nuclear emergency response ROD... more Mesoscale WRF meteorological model, adapted to provide a system of nuclear emergency response RODOS with operational meteorological information for the conditions of Rivne NPP was successfully verified on the basis of the measurement data of RNPP meteostation. Miscalculations of wind direction near RNPP are local in nature and reduce with improving the quality of the topography data and land use categories. Joint use of detailed SRTM topography and MODIS land-use with 15 second resolution allowed reducing bias error in wind direction more than by 20%.

Влияние неоднородностей температуры поверхности на теплообмен воздуха с землей

In the paper, the air flow process from the cold water surface onto the warm land surface was sim... more In the paper, the air flow process from the cold water surface onto the warm land surface was simulated. The comparisons of calculations with measurements were performed as well. The calculations show that the heat flux in the narrow coastal zone may be more than 20% higher than the values of heat fluxes calculated from the assumption of horizontal homogeneity of the surface layer. Thus, the horizontal inhomogeneity of the atmosphere must be taken into account in the calculation of the cooling water, the horizontal size of which has a scale of ~100 m.

Validation of an Inverse Method for the Source Determination of a Hazardous Airborne Material Released from a Point Source in an Urban Environment

An improved inverse method was presented recently for the estimation of the location and the rate... more An improved inverse method was presented recently for the estimation of the location and the rate of an unknown point stationary source of passive atmospheric pollutant in a complex urban geometry. The inverse method was incorporated in the well-established and updated version of the ADREA-HF Computational Fluid Dynamics code. The key improvement of the proposed inverse method implementation lies in a two-step segregated approach combining a correlation and cost functions. At first only the source coordinates are analyzed using a correlation function of measured and calculated concentrations. In the second step the source rate is identified by minimizing a quadratic cost function. The validation of the new algorithm is performed by simulating the MUST wind tunnel experiment. Overall, we observed significant improvement, compared to previous implementations, on reconstructing the source information (location and rate).

Evaluation of one-dimensional model of C-14 atmospheric transport in vegetated canopies

Journal of Environmental Radioactivity, 2021

The evaluation of the previously developed one-dimensional model of radiocarbon atmospheric trans... more The evaluation of the previously developed one-dimensional model of radiocarbon atmospheric transport in vegetated canopies against C-14 concentration data collected at the site of SMEAR-II research station was presented. In most cases, the simulated vertical profiles of C-14 concentrations within the canopy layer agreed reasonably with measurements, the correlation coefficient of simulated vs. observed concentrations was 0.72. The developed model could be used to evaluate vertical variations of C-14 concentrations in vegetated canopy layers.

Simulation study of radionuclide atmospheric transport after wildland fires in the Chernobyl Exclusion Zone in April 2020

Atmospheric Pollution Research, 2021

Abstract This paper presents model results for the dispersion of radionuclides released into the ... more Abstract This paper presents model results for the dispersion of radionuclides released into the atmosphere by intense forest fires in the Chernobyl Exclusion Zone in April 2020. The 137Cs activity concentration in the surface air is calculated on a regional scale (in Ukraine) and a local scale (within the Chernobyl Exclusion Zone). The 137Cs activity in the surface air of Kyiv was found to have reached 2–4 mBq m−3 during the period April 4–20. The results presented in this paper are generally consistent with measured data pertaining to radioactive contamination in Kyiv and areas around several nuclear power plants in Ukraine. The total effective dose to the population of Kyiv during the fire period was estimated to be 5.7 nSv from external exposure and the inhalation of 137Cs and 90Sr, rising to 30 nSv by the end of 2020. This is about 0.003% of the annual permissible level of exposure of the population. A committed effective dose of about 16 nSv was estimated for the personnel of the Chernobyl nuclear power plant from the inhalation of 137Cs and 90Sr during the 2020 forest fires. A method for estimating the radionuclide activity emissions during wildland fires in radioactively contaminated areas is proposed. This method is based on satellite measurement data of the fire radiative power, the radionuclide inventory in the fire area, and an emission factor for radioactive particles.

The use of relaxation methods in the WRF model for the analysis of meteorological conditions in Ukraine over a long period

Mathematical machines and systems, 2020

The possibility of using grid and spectral relaxation methods and other options in the WRF mesosc... more The possibility of using grid and spectral relaxation methods and other options in the WRF mesoscale model for long-term continuous calculations has been investigated. Results of comparison of selected me-teorological parameters with surface measurements are presented. The basic recommendations for select-ing the optimal combination of long-term calculation parameters are given. The use of the selected param-eters allowed to obtain continuous meteorological fields over a long period (several months), which are well consistent with surface measurements, retain large scale synoptic structures and have a deviation from measurements commensurate with the results of short-term simulations over corresponding time peri-od. The selected optimal combination of parameters allowed us to perform continuous calculation for the period from January 1, 2019 to November 6, 2019 without accumulating errors. In a long-run calculation of meteorological conditions in Ukraine with spatial resolution 0.15...

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Inverse identification of unknown finite-duration air pollutant release from a point source in urban environment

Atmospheric Environment, 2018

In this work, we present an inverse computational method for the identification of the location, ... more In this work, we present an inverse computational method for the identification of the location, start time, duration and quantity of emitted substance of an unknown air pollution source of finite time duration in an urban environment. We considered a problem of transient pollutant dispersion under stationary meteorological fields, which is a reasonable assumption for the assimilation of available concentration measurements within 1 h from the start of an incident. We optimized the calculation of the source-receptor function by developing a method which requires integrating as many backward adjoint equations as the available measurement stations. This resulted in high numerical efficiency of the method. The source parameters are computed by maximizing the correlation function of the simulated and observed concentrations. The method has been integrated into the CFD code ADREA-HF and it has been tested successfully by performing a series of source inversion runs using the data of 200 individual realizations of puff releases, previously generated in a wind tunnel experiment.

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Pilot study with complex simulation of atmospheric pollution in Kyiv

Mathematical machines and systems, 2020

УДК 528.9 І.В. КОВАЛЕЦЬ * , О.В. ХАЛЧЕНКОВ * , В.І. НОЧВАЙ * ПІЛОТНЕ ДОСЛІДЖЕННЯ З КОМПЛЕКСНОГО М... more УДК 528.9 І.В. КОВАЛЕЦЬ * , О.В. ХАЛЧЕНКОВ * , В.І. НОЧВАЙ * ПІЛОТНЕ ДОСЛІДЖЕННЯ З КОМПЛЕКСНОГО МОДЕЛЮВАННЯ АТМОСФЕРНОГО ЗАБРУДНЕННЯ М. КИЇВ * Інститут проблем математичних машин и систем НАН України, м. Київ, Україна Анотація. У роботі вперше проведено пілотне моделювання атмосферного забруднення у м. Київ від усіх відомих джерел діоксиду азоту, діоксиду сірки та аміаку. Для моделювання використано як дані звітності Держстатистики «2-ТП Повітря» щодо річних обсягів викидів від стаціонарних джерел у м. Київ, так і дані міжнародної георозподіленої бази даних викидів EMEP, яка складається на підставі звітів про обсяги викидів від окремих країн. Також було проведено оцінку обсягу та просторового розподілу викидів SO2 та NO2 від автотранспорту. Оцінки EMEP щодо викидів від стаціонарних джерел для усіх розглянутих речовин завжди більше, ніж відповідні дані зі звітів Держстатистики. Автотранспорт, згідно із проведеними оцінками, відповідає менше ніж за 50% викидів SO2 та NO2 у м. Київ. Попри не дуже реалістичний просторовий розподіл викидів у даних EMEP, моделювання на основі цих даних дозволяє отримати краще співпадіння результатів розрахунків із даними вимірів, ніж моделювання на основі даних емісій зі звітів Держстатистики. Але навіть у сценарії викидів EMEP розраховані концентрації SO2 та NO2 занижені у порівнянні з даними вимірів приблизно у 2 рази, що свідчить про відповідне заниження обсягів викидів у даних EMEP та набагато більше заниження викидів у звітах Держстатистики. Щодо аміаку, навіть у сценарії EMEP, в якому емісії NH3 у декілька разів перевищують відповідні обсяги зі звітів Держстатистики, розраховані концентрації у 7-25 разів занижені у порівнянні з даними вимірів NH3. З отриманих результатів можна зробити висновок, що на державному рівні у даних Держстатистики наявна інформація тільки про декілька відсотків від загального обсягу викидів аміаку у м. Київ. Результати роботи свідчать про необхідність невідкладного виконання рекомендацій експертів EMEP, наявних в опублікованій рецензії на Національний звіт України за даним протоколом, і, в першу чергу, складання і верифікація георозподіленої інвентаризації викидів згідно з методиками EMEP.

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Radionuclides deposition on sea surface following hypothetical accidental releases at Korean nuclear power plant

Stochastic Environmental Research and Risk Assessment, Dec 30, 2023

Modeling of Radioactive Contamination of the Black Sea and Its Impact on Humans Due to Hypothetical Heavy Accident at the Zaporizhzhia NPP

Lecture notes in networks and systems, 2023

Long-Term Contamination of the Arabian Gulf as a Result of Hypothetical Nuclear Power Plant Accidents

Journal of Marine Science and Engineering

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Determination of the parameters for the calculation of dry and wet deposition of chemicals in the Povitrya system

Mathematical machines and systems

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Geo-information web-system for presenting the results of the inventory of air pollution emis-sions in Kyiv

Mathematical machines and systems

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AGU Fall Meeting Abstracts, Dec 1, 2019

Математические машины и системы, 2017

Ensemble Data Assimilation of Concentration Measurements Following the Accidental Release of a Contaminant in the Ocean: Method Testing in an Idealized Setting

Pure and Applied Geophysics, 2022

Ассимиляция данных в трехмерной модели распространения радионуклидов в водоемах тритокс системы Родос

Flood forecasting and flood inundation mapping system developed for Ukrainian parts of Prut and Siret river basins within EAST AVERT project

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Використання системи wrf-україна для прогнозування агрометеорологічних умов

Web-система прогнозування метеорологічних умов для довільної території на детальних сітках

Адаптация метеорологической модели WRF для прогнозирования полей ветра вокруг Ривненской АЭС

Влияние неоднородностей температуры поверхности на теплообмен воздуха с землей

Validation of an Inverse Method for the Source Determination of a Hazardous Airborne Material Released from a Point Source in an Urban Environment

Evaluation of one-dimensional model of C-14 atmospheric transport in vegetated canopies

Journal of Environmental Radioactivity, 2021

Simulation study of radionuclide atmospheric transport after wildland fires in the Chernobyl Exclusion Zone in April 2020

Atmospheric Pollution Research, 2021

The use of relaxation methods in the WRF model for the analysis of meteorological conditions in Ukraine over a long period

Mathematical machines and systems, 2020

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Inverse identification of unknown finite-duration air pollutant release from a point source in urban environment

Atmospheric Environment, 2018

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Pilot study with complex simulation of atmospheric pollution in Kyiv

Mathematical machines and systems, 2020

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