Atmospheric Composition and Regional Climate Studies in Bulgaria

A special issue of Atmosphere (ISSN 2073-4433). This special issue belongs to the section "Climatology".

Deadline for manuscript submissions: closed (22 April 2022) | Viewed by 28173

Special Issue Editors


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Guest Editor
National Institute of Geophysics, Geodesy and Geography—Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 3 1113 Sofia, Bulgaria
Interests: air pollution transport modelling; planetary boundary layer dynamics; mesoscale flow systems; adjoined functions and inversed air pollution problems; regional climate modelling
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
National Institute of Geophysics, Geodesy and Geography—Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 3 1113 Sofia, Bulgaria
Interests: computer simulations of regional climate; air pollution transport; air quality; quality of life and health risk
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Тhe Special Issue “Atmospheric composition and regional climate studies in Bulgaria” is focused on the following two problems, which are of great societal and scientific importance.

1) The air forms human beings' living environment, and a number of atmospheric parameters, such as chemical composition and physical parameters (e.g., temperature, humidity, wind, and pressure) have great importance for the quality of life and human health.

2) Global warming is a consequence of ongoing changes in the circulation of the ocean–atmosphere system, which leads not only to changes in temperature but also to changes in the spatial/temporal distribution of precipitation hence the global water budgets, and changes in the characteristics and spatial/temporal distribution of unfavorable and catastrophic events (drought, storms, hail, floods, fires, sea waves, soil erosion, etc.). The current climate and the future climate changes will have an influence on ecosystems, on all sectors of the economy and on every aspect of human activity and quality of life. The regional/local characteristics of the climate changes cannot be predicted correctly by the global models, so the regional/local-scale specifics in climate changes and their consequences have to be taken into account.

Тhe Special Issue aims to promote atmospheric studies in Bulgaria in particular in the fields of atmospheric composition and climatic research. Papers are welcomed on air quality, the impact of air quality on environment and human health, the origin of the air pollution and the processes that form it, current and future regional climates for different global climate change scenarios, regional climate impacts on the environment and quality of life, computer simulation validation and sensitivity studies, interactions of different scales, and evaluation the effect of resolution on the simulated results.

Prof. Dr. Kostadin Ganev
Dr. Georgi Gadzhev
Guest Editors

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Keywords

  • atmospheric composition
  • atmospheric composition impact on environment and quality of life
  • operation air quality control systems
  • regional climate
  • regional climate changes
  • climate indices
  • regional climate impacts on environment
  • computer simulations
  • data analysis
  • instrumental studies

Published Papers (12 papers)

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Editorial

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2 pages, 161 KiB  
Editorial
Editorial for the Special Issue “Atmospheric Composition and Regional Climate Studies in Bulgaria”
by Kostadin Ganev and Georgi Gadzhev
Atmosphere 2022, 13(10), 1547; https://doi.org/10.3390/atmos13101547 - 21 Sep 2022
Viewed by 881
Abstract
The Special Issue “Atmospheric composition and regional climate studies in Bulgaria” is focused on the following two problems, which are of great societal and scientific importance: [...] Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)

Research

Jump to: Editorial

20 pages, 2182 KiB  
Article
Spatio-Temporal Variation of Extreme Heat Events in Southeastern Europe
by Krastina Malcheva, Lilia Bocheva and Hristo Chervenkov
Atmosphere 2022, 13(8), 1186; https://doi.org/10.3390/atmos13081186 - 27 Jul 2022
Cited by 6 | Viewed by 2254
Abstract
Many studies in the last few years have been dedicated to the increasing temperatures and extreme heat in Europe since the second half of the 20th century because of their adverse effects on ecosystems resilience, human health, and quality of life. The present [...] Read more.
Many studies in the last few years have been dedicated to the increasing temperatures and extreme heat in Europe since the second half of the 20th century because of their adverse effects on ecosystems resilience, human health, and quality of life. The present research aims to analyze the spatio-temporal variations of extreme heat events in Southeastern Europe using daily temperature data from 70 selected meteorological stations and applying methodology developed initially for the quantitative assessment of hot weather in Bulgaria. We demonstrate the suitability of indicators based on maximum temperature thresholds to assess the intensity (i.e., magnitude and duration) and the tendency of extreme heat events in the period 1961–2020 both by individual stations and the Köppen’s climate zones. The capability of the used intensity-duration hot spell model to evaluate the severity of extreme heat events has also been studied and compared with the Excess Heat Factor severity index on a yearly basis. The study provides strong evidence of the suitability of the applied combined approach in the investigation of the spatio-temporal evolution of the hot weather phenomena over the considered domain. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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28 pages, 40490 KiB  
Article
Large-Scale Saharan Dust Episode in April 2019: Study of Desert Aerosol Loads over Sofia, Bulgaria, Using Remote Sensing, In Situ, and Modeling Resources
by Zahari Peshev, Atanaska Deleva, Liliya Vulkova and Tanja Dreischuh
Atmosphere 2022, 13(6), 981; https://doi.org/10.3390/atmos13060981 - 17 Jun 2022
Cited by 7 | Viewed by 1844
Abstract
Emissions of immense amounts of desert dust into the atmosphere, spreading over vast geographical areas, are in direct feedback relation with ongoing global climate changes. An extreme large-scale Saharan dust episode occurred over Mediterranean and Europe in April 2019, driven by a dynamic [...] Read more.
Emissions of immense amounts of desert dust into the atmosphere, spreading over vast geographical areas, are in direct feedback relation with ongoing global climate changes. An extreme large-scale Saharan dust episode occurred over Mediterranean and Europe in April 2019, driven by a dynamic blocking synoptic pattern (omega block) creating conditions for a powerful northeastward circulation of air masses rich in dust and moisture. Here, we study and characterize the effects of related dust intrusion over Sofia, Bulgaria, using lidar remote sensing combined with in situ measurements, satellite imagery, and modeling data. Optical and microphysical parameters of the desert aerosols were obtained and vertically profiled, namely, backscatter coefficients and backscatter-related Ångström exponents, as well as statistical distributions of the latter as qualitative analogs of the actual particle size distributions. Dynamical and topological features of the dust-dominated aerosol layers were determined. Height profiles of the aerosol/dust mass concentration were obtained by synergistic combining and calibrating lidar and in situ data. The comparison of the retrieved mass concentration profiles with the dust modeling ones shows a satisfactory compliance. The local meteorological conditions and the aerosol composition and structure of the troposphere above Sofia during the dust event were seriously affected by the desert air masses. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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13 pages, 5052 KiB  
Article
Black Sea Freezing and Relation to the Winter Conditions in 2006–2021
by Mirna Matov, Elisaveta Peneva and Vasko Galabov
Atmosphere 2022, 13(6), 974; https://doi.org/10.3390/atmos13060974 - 16 Jun 2022
Cited by 1 | Viewed by 4442
Abstract
Black Sea freezing in winter is observed regularly in its northern parts and near the Kerch Strait. The reason for this is the relatively shallow northwestern shelf part and the river inflow of the three major European rivers Danube, Dnieper, and Dniester, as [...] Read more.
Black Sea freezing in winter is observed regularly in its northern parts and near the Kerch Strait. The reason for this is the relatively shallow northwestern shelf part and the river inflow of the three major European rivers Danube, Dnieper, and Dniester, as well as Don through the Azov Sea, carrying a large amount of fresh water to this part of the Black Sea. The global warming that has been observed in recent decades has made these episodes less intense; nevertheless, they exist and impact people who live n the area. The aim of this study is to analyze the extent of sea-ice variability in the last 15 years, observed by satellite observations, and to describe the weather conditions favorable for freezing to occur. It is found that, in 2006, 2012 and 2017, sea ice extended unusually southward, which is related to the unusually cold winter and weather conditions in these years. The weather patterns associated with the periods of maximal sea ice in the Black Sea are discussed. In addition, we analyze how the winter conditions change in the period 1926–2021 by combining different data sources. The winter is classified as cold, moderate or mild through the Winter Severity Index following a previously published methodology. The findings in our paper could help to monitor and predict these events and to inform the interested end-users. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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22 pages, 4464 KiB  
Article
Using a Digital Twin to Study the Influence of Climatic Changes on High Ozone Levels in Bulgaria and Europe
by Zahari Zlatev and Ivan Dimov
Atmosphere 2022, 13(6), 932; https://doi.org/10.3390/atmos13060932 - 08 Jun 2022
Cited by 8 | Viewed by 2012
Abstract
High concentration levels of air pollutants may cause damage to plants, animals, and the health of some groups of human beings. Therefore, it is important to investigate different topics related to the high air pollution levels and to find reliable answers to the [...] Read more.
High concentration levels of air pollutants may cause damage to plants, animals, and the health of some groups of human beings. Therefore, it is important to investigate different topics related to the high air pollution levels and to find reliable answers to the questions about the possible damages, which might take place when these levels exceed some limits. A few of the numerous questions, the answers of which are highly desirable, are listed below: (a) When are the air pollution levels dangerous? (b) What is the reason for the increased air pollution levels? (c) How can the air pollution levels be decreased? (d) Will the future climate changes result in higher and more dangerous air pollution levels? It is necessary to study carefully many issues connected with the distribution of air pollutants in a given region and with the reasons for the increases of the concentrations to high levels, which might be damaging. In order to do this, it is necessary to develop a Digital Twin of all relevant physical processes in the atmosphere and to use after that this tool in different applications. Such a tool, its name is DIGITAL AIR, has been created. Digital Twins are becoming more and more popular). Many complex problems, arising taking place in very complicated surroundings, can be handled and resolved successfully by applying Digital Twins. The preparation of such a digital tool as well as its practical implementation in the treatment of a special problem, the increase of some potentially dangerous ozone levels, will be discussed and tested in this paper. The Unified Danish Eulerian Model (UNI-DEM) is a very important part of DIGITAL AIR. This mathematical model, UNI-DEM, can be applied in many different studies related to damaging effects caused by high air pollution levels. We shall use it in this paper to get a reliable answer to a very special but extremely important question: will the future climatic changes lead to an increase in the ozone pollution levels in Bulgaria and Europe, which can potentially become dangerous for human health? Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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18 pages, 4169 KiB  
Article
Latitude Dependence of the Total Ozone Trends for the Period 2005–2020: TOC for Bulgaria in the Period 1996–2020
by Rumiana Bojilova, Plamen Mukhtarov and Nikolay Miloshev
Atmosphere 2022, 13(6), 918; https://doi.org/10.3390/atmos13060918 - 06 Jun 2022
Cited by 3 | Viewed by 1406
Abstract
The present study examines a long-term statistical trend analysis of Total Ozone Content (TOC) data from the AURA satellite for latitudes 60° and 60° S. A methodology for eliminating the strong dependence on the season has been applied by introducing the relative deviation [...] Read more.
The present study examines a long-term statistical trend analysis of Total Ozone Content (TOC) data from the AURA satellite for latitudes 60° and 60° S. A methodology for eliminating the strong dependence on the season has been applied by introducing the relative deviation of the average monthly TOC from the climatological average. The analysis presents comparisons of the trends of the zonal average values of TOC and its relative values. In addition, the standard error of both parameters is calculated. The course of the obtained mass of Ozone (O3) and its trend for the period 2005–2020 is presented, and a division is made into three areas: (i) from 30° S to 30° N, (ii) from 30° S to 60° S, and (iii) from 30° N to 60° N. The last part of this study demonstrates the trends of TOC and relative TOC for Bulgaria in the period 1996–2020. The main results of this study show that (a) in the considered latitude range, a slow but steady increase in O3 prevails, (b) the main part of the O3 mass is in low and mid-latitudes, and (c) the general trend in O3 mass for both hemispheres is determined by the positive trend in the southern hemisphere. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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29 pages, 9035 KiB  
Article
Optical and Microphysical Properties of the Aerosol Field over Sofia, Bulgaria, Based on AERONET Sun-Photometer Measurements
by Tsvetina Evgenieva, Ljuan Gurdev, Eleonora Toncheva and Tanja Dreischuh
Atmosphere 2022, 13(6), 884; https://doi.org/10.3390/atmos13060884 - 29 May 2022
Cited by 7 | Viewed by 2183
Abstract
An analysis of the optical and microphysical characteristics of aerosol passages over Sofia City, Bulgaria, was performed on the basis of data provided by the AErosol RObotic NETwork (AERONET). The data considered are the result of two nearly complete annual cycles of passive [...] Read more.
An analysis of the optical and microphysical characteristics of aerosol passages over Sofia City, Bulgaria, was performed on the basis of data provided by the AErosol RObotic NETwork (AERONET). The data considered are the result of two nearly complete annual cycles of passive optical remote sensing of the atmosphere above the Sofia Site using a Cimel CE318-TS9 sun/sky/lunar photometer functioning since 5 May 2020. The values of the Aerosol Optical Depth (AOD) and the Ångström Exponent (AE) measured during each annual cycle and the overall two-year cycle exhibited similar statistics. The two-year mean AODs were 0.20 (±0.11) and 0.17 (±0.10) at the wavelengths of 440 nm (AOD440) and 500 nm, respectively. The two-year mean AEs at the wavelength pairs 440/870 nm (AE440/870) and 380/500 nm were 1.45 (±0.35) and 1.32 (±0.29). The AOD values obtained reach maxima in winter-to-spring and summer and were about two times smaller than those obtained 15 years ago using a hand-held Microtops II sun photometer. The AOD440 and AE440/870 frequency distributions outline two AOD and three AE modes, i.e., 3 × 2 groups of aerosol events identifiable using AOD–AE-based aerosol classifications, additional aerosol characteristics, and aerosol migration models. The aerosol load over the city was estimated to consist most frequently of urban (63.4%) aerosols. The relative occurrences of desert dust, biomass-burning aerosols, and mixed aerosols were, respectively, 8.0%, 9.1% and 19.5%. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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21 pages, 3910 KiB  
Article
Response of Very Small Glaciers to Climate Variations and Change: Examples from the Pirin Mountains, Bulgaria
by Emil M. Gachev
Atmosphere 2022, 13(6), 859; https://doi.org/10.3390/atmos13060859 - 24 May 2022
Cited by 3 | Viewed by 1631
Abstract
Very small glaciers (glacierets) react strongly to climatic variations. This is well expressed in their interannual size changes, which are most evident in autumn, at the end of the glacial mass balance year. This study presents results from the detailed research of two [...] Read more.
Very small glaciers (glacierets) react strongly to climatic variations. This is well expressed in their interannual size changes, which are most evident in autumn, at the end of the glacial mass balance year. This study presents results from the detailed research of two very small glaciers in the highest northern part of the Pirin Mountains of Bulgaria: Snezhnika and Banski suhodol. Systematic size measurements of these firn-ice bodies, which started in the 1990s and have been made simultaneously for a period of 13 years, show large inter-annual amplitudes against the background of a decreasing trend in response to climate warming. However, the relations are not straightforward, which is demonstrated when comparing size changes to climate data, including logger data obtained from glacier vicinity. This fact makes predictions for the changes in the local climate of high mountain cirques still relatively uncertain. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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19 pages, 38561 KiB  
Article
Time Series Forecasting of Air Quality: A Case Study of Sofia City
by Evgeniy Marinov, Dessislava Petrova-Antonova and Simeon Malinov
Atmosphere 2022, 13(5), 788; https://doi.org/10.3390/atmos13050788 - 12 May 2022
Cited by 8 | Viewed by 4972
Abstract
Air pollution has a significant impact on human health and the environment, causing cardiovascular disease, respiratory infections, lung cancer and other diseases. Understanding the behavior of air pollutants is essential for adequate decisions that can lead to a better quality of life for [...] Read more.
Air pollution has a significant impact on human health and the environment, causing cardiovascular disease, respiratory infections, lung cancer and other diseases. Understanding the behavior of air pollutants is essential for adequate decisions that can lead to a better quality of life for citizens. Air quality forecasting is a reliable method for taking preventive and regulatory actions. Time series analysis produces forecasting models, which study the characteristics of the data points over time to extrapolate them in the future. This study explores the trends of air pollution at five air quality stations in Sofia, Bulgaria. The data collected between 2015 and 2019 is analyzed applying time series forecasting. Since the time series analysis works on complete data, imputation techniques are used to deal with missing values of pollutants. The data is aggregated by granularity periods of 3 h, 6 h, 12 h, 24 h (1 day). The AutoRegressive Integrated Moving Average (ARIMA) method is employed to create statistical analysis models for the prediction of pollutants’ levels at each air quality station and for each granularity, including carbon oxide (CO), nitrogen dioxide (NO2), ozone (O3) and fine particles (PM2.5). In addition, the method allows us to find out whether the pollutants’ levels exceed the limits prescribed by the World Health Organization (WHO), as well as to investigate the correlation between levels of a given pollutant measured in different air quality stations. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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19 pages, 9563 KiB  
Article
Influence of the Grid Resolutions on the Computer-Simulated Surface Air Pollution Concentrations in Bulgaria
by Georgi Gadzhev, Kostadin Ganev and Plamen Mukhtarov
Atmosphere 2022, 13(5), 774; https://doi.org/10.3390/atmos13050774 - 10 May 2022
Cited by 2 | Viewed by 1433
Abstract
The present study aims to demonstrate the effects of horizontal grid resolution on the simulated pollution concentration fields over Bulgaria. The computer simulations are performed with a set of models used worldwide—the Weather Research and Forecasting Model (WRF)—the meteorological preprocessor, the Community Multiscale [...] Read more.
The present study aims to demonstrate the effects of horizontal grid resolution on the simulated pollution concentration fields over Bulgaria. The computer simulations are performed with a set of models used worldwide—the Weather Research and Forecasting Model (WRF)—the meteorological preprocessor, the Community Multiscale Air Quality Modeling System (CMAQ)—chemical transport model, Sparse Matrix Operator Kernel Emissions (SMOKE)—emission model. The large-scale (background) meteorological data used in the study were taken from the ‘NCEP Global Analysis Data’ with a horizontal resolution of 1° × 1°. Using the ‘nesting’ capabilities of the WRF and CMAQ models, a resolution of 9 km was achieved for the territory of Bulgaria by sequentially solving the task in several consecutive nested areas. Three cases are considered in this paper: Case 1: The computer simulations result from the domain with a horizontal resolution (both of the emission source description and the grid) of 27 km.; Case 2: The computer simulations result from the domain with a horizontal resolution (both of the emission source description and the grid) of 9 km.; Case 3: A hybrid case with the computer simulations performed with a grid resolution of 9 km, but with emissions such as in the 27 km × 27 km domain. The simulations were performed, for all the three cases, for the period 2007–2014 year, thus creating an ensemble large and comprehensive enough to reflect the most typical atmospheric conditions with their typical recurrence. The numerical experiments showed the significant impact of the grid resolution not only in the pollution concentration pattern but also in the demonstrated generalized characteristics. Averaged over a large territory (Bulgaria); however, the performances for cases one and two are quite similar. Bulgaria is a country with a complex topography and with several considerably large point sources. Thus, some of the conclusions made, though based on Bulgarian-specific experiments, may be of general interest. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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14 pages, 3818 KiB  
Article
NEX-GDDP Multimodel Ensemble vs. E-OBS—Evaluation of the Extreme Temperatures and Precipitation over Southeast Europe: Historical Comparison
by Hristo Chervenkov and Kiril Slavov
Atmosphere 2022, 13(4), 581; https://doi.org/10.3390/atmos13040581 - 04 Apr 2022
Cited by 7 | Viewed by 1917
Abstract
The present study evaluates the National Aeronautics Space Administration (NASA) Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset that provides statistically downscaled CMIP5 historical and future climate projections of the daily precipitation sum and extreme temperatures at high spatial resolution. A multimodel ensemble [...] Read more.
The present study evaluates the National Aeronautics Space Administration (NASA) Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset that provides statistically downscaled CMIP5 historical and future climate projections of the daily precipitation sum and extreme temperatures at high spatial resolution. A multimodel ensemble from all 21 available models is composed and compared against gridded observations from E-OBS. The study is performed over Southeast Europe for the whole time span of the historical period of NEX-GDDP 1950–2005. The performance of the NEX-GDDP data was evaluated at multiple time scales such as annual, seasonal, monthly, and daily. The skill of the multimodel ensemble to reproduce the interannual variability, as well as the long-term trend, is also evaluated. Moreover, key climate indices of the Expert Team on Climate Change Detection and Indices (ETCCDI), derived from the ensemble extreme temperatures and precipitation are superimposed on their counterparts based on the reference dataset E-OBS. Findings of the performed research indicate that NEX-GDDP parameters are in good agreement with the reference over the considered period on monthly, seasonal and annual scales which agrees with the outcomes from similar studies for other parts of the world. There are also no systematic differences in the pattern of the biases of the minimum and maximum temperature. Generally, the multimodel ensemble reproduces the extreme temperatures significantly better than the precipitation sum. The analysis reveals also the nonnegligible inefficiency of the NEX-GDDP ensemble to reproduce the long-term trend of the considered parameters as well as the climate extremes expressed with the ETCCDI indices. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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21 pages, 3886 KiB  
Article
Sulfur and Nitrogen Depositions in BULGARIA—Model Results and Observations
by Emilia Georgieva, Elena Hristova, Dimiter Syrakov, Maria Prodanova, Ilian Gospodinov and Blagorodka Veleva
Atmosphere 2022, 13(2), 343; https://doi.org/10.3390/atmos13020343 - 18 Feb 2022
Cited by 1 | Viewed by 1762
Abstract
Atmospheric deposition processes are of primary importance for human health, forests, agricultural lands, aquatic bodies, and ecosystems. South-East Europe is still characterized by numerous hot spots of elevated sulfur deposition, despite the reduction in European emission sources. The purpose of this study is [...] Read more.
Atmospheric deposition processes are of primary importance for human health, forests, agricultural lands, aquatic bodies, and ecosystems. South-East Europe is still characterized by numerous hot spots of elevated sulfur deposition, despite the reduction in European emission sources. The purpose of this study is to discuss the results from two chemical transport models and observations for wet and dry depositions of sulfur (S), reduced nitrogen (RDN) and oxidized nitrogen (OXN) in Bulgaria in 2016–2017. The spatial distribution and the domain main deposition values by EMEP MSC-W (model of the MSC-W Centre of the Co-operative Programme for Monitoring and Evaluation of the Long-range Transmissions of Air Pollutants in Europe) and BgCWFS (Bulgarian Chemical Weather Forecast System) demonstrated S wet depositions to be higher than N depositions, and identified a rural area in south-east Bulgaria as a possible hot-spot. The chemical analysis of deposition samples at three sites showed a prevalence of sulfate in the western part of the country, and prevalence of Cl and Na at a coastal site. The comparison between modeled and observed depositions demonstrated that both models captured the prevalence of S wet depositions at all sites. Better performance of BgCWFS with an average absolute value of the normalized mean bias of 16% was found. Full article
(This article belongs to the Special Issue Atmospheric Composition and Regional Climate Studies in Bulgaria)
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