This study examines the spatio-temporal variations of ambient air pollution from fine particulates below 2.5 µm (PM2.5) and particulate matter below 10 µm (PM10) in three of the most polluted provinces in Iran, namely Tehran, Isfahan, and Khuzestan, over a 6-year period (2016–2021). The results reveal distinct patterns of PM10 and PM2.5 concentrations since in Tehran, the highest PM10 and PM2.5 levels occur in winter, while PM2.5 is lowest from March to May. Khuzestan experiences the highest pollution levels in summer due to dust storms, while Isfahan exhibits pollution levels and annual patterns similar to Tehran. Strong correlations are observed between PM10 and PM2.5 concentrations at stations in Tehran and Khuzestan Provinces, suggesting common sources and variation in both coarse and fine PM, with average PM2.5/PM10 ratios of 0.39–0.42, suggesting the dominance of dust. Furthermore, the analysis identifies the role of atmospheric stability, wind speed, and dust storms in controlling the PM levels in the three provinces. Lifetime cancer risks have been identified as unacceptably high, exceeding the threshold limit of 10−4, while Hazard Quotient (HQ) values above 1 indicate a high non-carcinogenic potential risk, particularly at stations in Khuzestan Province. The Excess Lifetime Cancer Risk (ELCR) values for PM2.5 exposure in the most populated Tehran Province range from 139.4 × 10−6 to 263.2 × 10−6, underscoring significant cancer risks across various monitoring sites. This study emphasizes the urgent need for targeted pollution control measures in each province to effectively mitigate the adverse health effects associated with high PM concentrations.

The relevance of studying the dynamics of ozone concentration in the troposphere is due to the fact that in high concentrations it is a strong poison and a powerful oxidant that extremely negatively impacts both biological structures and the environment. Therefore, the dynamics of ozone concentration require urgent study in different areas of the Earth. Based on monitoring data, the paper examines the distribution of tropospheric ozone in Russia in 2023 in the surface air layer, as well as its vertical distribution based on the results of aircraft sensing. It is shown that the maximum permissible daily average concentrations established by the national hygienic standard, including maximal one-time, daily average, and annual average, were exceeded at all measurement sites. The current situation necessitates widespread public awareness of the results of monitoring and the development of environmental protection measures to reduce the concentration of ozone and its precursors in the surface air layer. The results of the work can be useful to specialists in the fields of atmospheric physics, climatology, and environmental protection, as well as to administrative bodies of different responsibility levels.

Озон в тропосфере в высоких концентрациях является сильнодействующим ядом и мощным окислителем, крайне негативно воздействующим на биологические объекты и объекты окружающей среды. Поэтому весьма актуально исследование динамики его концентрации во всех регионах планеты. По данным мониторинга рассматривается распределение тропосферного озона на территории России в 2023 г. в приземном слое воздуха, а также его вертикальное распределение по результатам самолетного зондирования. Показано, что во всех пунктах измерений превышались предельно допустимые среднесуточные концентрации, установленные отечественным гигиеническим нормативом: максимальные разовые, среднесуточные и среднегодовые. В связи со сложившейся ситуацией необходимы широкое информирование населения о результатах мониторинга и разработка природоохранных мероприятий по снижению уровня концентрации озона и его прекурсоров в приземном слое воздуха. Результаты работы могут быть полезны специалистам в области физики атмосферы, климатологии, охраны окружающей среды, а также административным органам разных уровней. The relevance of studying the dynamics of ozone concentration is due to the fact that at high concentrations it is a potent poison and a powerful oxidizer that extremely negatively impacts both biological objects and the environment. Based on the monitoring data, the paper examines the distribution of tropospheric ozone in Russia in 2023 in the surface air layer, as well as its vertical distribution based on the results of aircraft sounding. It is shown that the maximum allowable daily average concentrations established by the domestic hygienic standard, maximum single, daily average, and annual average, were exceeded at all measurement points. The current situation necessitates widespread public awareness of the results of monitoring and the development of environmental measures to reduce the concentration of ozone and its precursors in the surface air layer.

В обсерватории «Фоновая» с осени 2021 года установлен 13-каскадный импактор высокого разрешения 125R NanoMoudi-II, способный селективно отбирать аэрозоль разного диапазона дисперсности с номинальными размерами: 10000, 5600, 3200, 1800, 1000, 560, 320, 180, 100, 56, 32, 18 и 10 нм. Кварцевые и тефлоновые фильтры используются для исследования ионно-элементного и органического состава фракций приземного фонового аэрозоля, соответственно. Анализ кварцевых фильтров производится в Иркутском лимнологическом институте СО РАН методами ионной хроматографии и ИСП-МС. Тефлоновые фильтры типа Grimm 1.113A используются для отбора и анализа органических аэрозолей методом ГХ-МС в ИХКГ СО РАН. Обсуждается химический состав отобранных в 2022 году проб продолжительностью от 6 до 16 суток, состав которых анализируется опробированными в 2021 г. методиками. Изменчивость содержания ионной компоненты аэрозоля в течение года достигает порядка величины, с максимумом в конце зимы и минимумом летом. «Зимний» пик основы ионной фракции - сульфат-аниона - лежит в области 0,56-1 мкм, смещаясь летом в область более мелких частиц 0,18-0,32 мкм. Для микроэлементов как временной ход концентраций, так и распределения по размерам имеют более сложный вид. A high-resolution 125R NanoMoudi-II impactor with 13 cascades has been installed at the "Fonovaya" Observatory since the autumn of 2021. It is capable of selectively sampling aerosols of varying size ranges with nominal sizes of 10000, 5600, 3200, 1800, 1000, 560, 320, 180, 100, 56, 32, 18, and 10 nm. Quartz and Teflon filters are used for studying the ionic-elemental and organic composition of ground-level background aerosol fractions, respectively. The analysis of the quartz filters is carried out at the Irkutsk Limnological Institute of the Siberian Branch of the Russian Academy of Sciences using ion chromatography and ICP-MS methods. Teflon filters of type Grimm 1.113A are utilized for sampling and analyzing organic aerosols using GC-MS in the Institute of Chemical Kinetics and Combustion of the Siberian Branch of the Russian Academy of Sciences. The chemical composition of samples collected in 2022 with exposure times ranging from 6 to 16 days is discussed, analyzed using methods tested in 2021. The variability of the ionic component of aerosol content throughout the year reaches significant levels, peaking in late winter and hitting a minimum in summer. The winter peak of the ionic fraction’s base—the sulfate anion—lies within the range of 0.56-1 µm, shifting to smaller particles of 0.18-0.32 µm in summer. For trace elements, both the temporal course of concentrations and the size distribution exhibit a more complex pattern. «Background» observatory, high-resolution impactor, ground-level background aerosol, ionic component of aerosol

Dust storms are one of the important natural hazards that affect the lives of inhabitants all around the world, especially in North Africa and the Middle East. In this study, wind speed, wind direction, and air temperature patterns are investigated in one of the dustiest cities in Sistan Basin, Zahedan City, located in southeast Iran, over a 17-year period (2004–2020) using a WRF model and ground observation data. The city is located near a dust source and is mostly affected by local dust storms. The World Meteorology Organization (WMO) dust-related codes show that the city was affected by local dust, with 52 percent of the total dust events occurring during the period (2004–2021). The city’s weather station reported that 17.5% and 43% were the minimum and maximum dusty days, respectively, during 2004–2021. The summer and July were considered the dustiest season and month in the city. Since air temperature, wind speed, and wind direction are important factors in dust rising and propagation, these meteorological factors were simulated using the Weather Research and Forecasting (WRF) model for the Zahedan weather station. The WRF model’s output was found to be highly correlated with the station data; however, the WRF simulation mostly overestimated when compared with station data during the study period (2004–2020). The model had a reasonable performance in wind class frequency distribution at the station, demonstrating that 42.6% of the wind was between 0.5 and 2, which is in good agreement with the station data (42% in the range of 0.5–2). So, the WRF model effectively simulated the wind class frequency distribution and the wind direction at Zahedan station, despite overestimating the wind speed as well as minimum, maximum, and average air temperatures during the 17-year period.

Dust storms are one of the major environmental hazards affecting the Middle East countries, and largely originate in vast deserts and narrow dried lake beds. This study analyzes the inter-annual variation in dust weather conditions from 2000 to 2020 using data obtained from ten meteorological stations located around dried (completely or partly) lakes in Northwest (Urmia Lake) and South (Bakhtegan Lake) Iran. Since the wind regime is one of the most important factors controlling dust emissions in the dust source areas, wind speed simulations from the Weather Research and Forecasting (WRF) Model for 134,113 grid points covering the Middle East area, with a resolution of 5 km, were analyzed and compared with wind measurements at the stations around Urmia and Bakhtegan Lakes from 2005 to 2015. The analysis shows that the annual number of dust days was highly variable, presenting a significant increase at the stations around Urmia Lake during 2008–2011 and at the stations around Bakhtegan Lake in 2007–2012. Eleven years of WRF simulations of the mean diurnal wind patterns revealed that the highest 10 m wind speed occurred mostly around the local noon (12 to 15 UTC), generally coinciding with the majority of the reported dust codes within this time frame, as a result of the association between wind speed and dust emissions (dust weather conditions) around these lake basins. Consequently, accurate wind simulation has high importance for unbiased numerical prediction and forecasting of dust conditions. The comparison between the measured mean monthly 10 m wind speed and WRF-simulated 10 m wind speed revealed that the model overestimated wind data in all the stations around the Bakhtegan Lake but performed better at reconstructing the wind speeds at stations around Urmia Lake. Furthermore, notable differences were observed between measured and simulated wind directions, thus leading to uncertainties in the simulations of the dust-plume transport.

Dried lake beds are one of the largest sources of dust in the world, causing environmental problems in the surrounding areas. In this study, the desiccated Urmia Lake was the primary source of dust for all nearby synoptic stations during the April 24-25, 2017 dust episode. Synoptic analysis revealed that the heavy dust storm was triggered by a strong Black Sea cyclone and a low-pressure system over central Iraq in conjunction with a vast high-pressure system. HYSPLIT-based trajectory analysis showed that high PM10 recorded over the Urmia Lake region on April 23-26, 2017, influenced western Azerbaijan, the south of the Caspian Sea, southwestern Kazakhstan, northwestern Uzbekistan, and western Turkmenistan. The dustiest air masses (PM10 > 400 µg m–3) affected the south of the Caspian Sea and western Azerbaijan. Furthermore, the WRF-Chem model was run to evaluate the spatial distribution of dust particles in the study region. The vertical profile revealed that the simulated dust concentration ascended to 5 km from the lake. The WRF-Chem dust schemes accurately simulated dust propagation and the vertical dust profile over Urmia Lake; however, the AFWA and GOCART dust schemes showed that PM10 fluctuating changes were earlier than the measured surface PM10 at five stations around Urmia Lake on April 23-26, 2017. Furthermore, the maximum amount anticipated by the model simulation was 12 h earlier than the maximum surface mass concentration of measured PM10 at the stations throughout the period.

Nowadays, dried lake beds constitute the largest source of saline dust storms, with serious environmental and health issues in the surrounding areas. In this study, we examined the spatial–temporal distribution of monthly and annual dust events of varying intensity (dust in suspension, blowing dust, dust storms) in the vicinity of the desiccated Urmia Lake in northwestern (NW) Iran, based on horizontal visibility data during 2009–2022. Dust in suspension, blowing dust and dust storm events exhibited different monthly patterns, with higher frequencies between March and October, especially in the southern and eastern parts of the Urmia Basin. Furthermore, the intra-annual variations in aerosol optical depth at 500 nm (AOD550) and Ångström exponent at 412/470 nm (AE) were investigated using Terra/Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) data over the Urmia Lake Basin (36–39°N, 44–47°E). Monthly distributions of potential coarse aerosol (AE < 1) sources affecting the lower troposphere over the Urmia Basin were reconstructed, synergizing Terra/Aqua MODIS AOD550 for AE < 1 values and HYSPLIT_4 backward trajectories. The reconstructed monthly patterns of the potential sources were compared with the monthly spatial distribution of Terra MODIS AOD550 in the Middle East and Central Asia (20–70°E, 20–50°N). The results showed that deserts in the Middle East and the Aral–Caspian arid region (ACAR) mostly contribute to dust aerosol load over the Urmia Lake region, exhibiting higher frequency in spring and early summer. Local dust sources from dried lake beds further contribute to the dust AOD, especially in the western part of the Urmia Basin during March and April. The modeling (DREAM8-NMME-MACC) results revealed high concentrations of near-surface dust concentrations, which may have health effects on the local population, while distant sources from the Middle East are the main controlling factors to aerosol loading over the Urmia Basin.

Dust particles are one of the most important aerosol types with various effects on atmospheric dynamics and thermodynamics, weather phenomena, atmospheric chemistry, air pollution and human health. In this study, both wind speed and direction are simulated by the WRF model in one of the dustiest cities, Zabol City, in east Iran during a 17 years period (2005-2021). The city was chosen because it’s located in a dust source and is mostly affected by local dust storms. The dust frequency is very high and at least one third of the year, dust-related codes are reported at the weather station of the city. Also, a high number of dust events occurs from May to September that is in coincidence with the Levar wind. Since both wind speed and wind direction are one of important factors in dust rising and propagation, especially near the dust sources, these parameters were simulated by WRF model in this study. WRF model well simulated both the wind direction and the wind class frequency distribution at Zabol station, while the model mostly overestimated the wind speed during the 17 years period.

The average monthly profiles of the dust extinction coefficient (ε) were analyzed according to the CALIOP lidar data from 2006–2021 for 24 cells (size of 2° × 5°) in the Aral-Caspian arid region (ACAR; 38–48°N, 50–70°E). Using the NOAA HYSPLIT_4 trajectory model and the NCEP GDAS1 gridded (resolution of 1° × 1°) archive of meteorological data, the array of >1 million 10-day forward trajectories (FTs) of air particles that started from the centers of the ACAR cells was calculated. On the basis of the FT array, the average seasonal heights of the mixed layer (ML) for the ACAR cells were reconstructed. Estimates of the average seasonal dust optical depth (DOD) were obtained for ACAR’s lower troposphere, for ACAR’s ML (“dust emission layer” (EL)), and for the lower troposphere above the ML (“dust transit layer” (TL)) above each of the ACAR cells. Using the example of ACAR, it is shown that the analysis of DOD for the EL, TL and the surface layer (SL; the first 200 m AGL) makes it possible to identify dusty surfaces that are not detected on DOD diagrams for the entire atmospheric column, as well as regions where the regular transport of aged dust from remote sources can generate false sources. Based on FT array, the fields of the potential contribution of both the ACAR’s dust transit and the ACAR’s dust emission layers as well as of the entire ACAR’s lower troposphere into the DOD of the surrounding and remote regions are retrieved using the original method of potential impact of a three-dimensional source (3D-PSI). It has been found out that ACAR dust spreads over almost the entire Northern Hemisphere; the south and southeast regions of the ACAR are subject to the maximum impact of the ACAR dust. Quantitative estimates of the potential contribution of ACAR dust to the regional DODs are given for a number of control sites in the Northern Hemisphere. The results could be useful for climatological studies.

-The paper presents data acquired by a comparative study of the vertical variability in the chemical composition and ratios of aerosol subdisperse fractions in snow layers chronologically correlated with the stratigraphically significant snowfall periods. These data highlight features of the concentrating of trace elements at reactive (geochemical) barriers in the snow profile. The ratio of three geochemically close groups of elements, such as siderophile, sulfophile, and lithophile elements, were found out to vary relatively little from one snow layer to another in the growing snow cover. Trajectory analysis of the transfer of air masses to which stratigraphically significant snowfalls were related to the observation site provides no evidence that the identified geochemical phenomenon can be explained by that the winter aerosol field that was formed above an urban area with different trajectories of air masses can be somehow inherited in the snow layers of the growing snow cover and thus affect the vertical distributions of trace elements. Evidence indicates that that the ratios of assemblages of trace elements in the discrete snow layers, which remain stable with the growth of the snow mass, can be employed as geochemical markers of stagnant zones in an urban heat island, and the method of geochemical sampling of a snow cover in its discrete layers at a rare network of urban meteorological observation sites is an efficient additional tool for studying microscale atmospheric processes and recovering information on characteristics of the transfer of pollutants in a spatially limited urban area.

The aim of the work was to study the isotopic characteristics of precipitation to establish the dependence of δ18O values on temperature at the time of precipitation and to get closer to understanding the processes that form the isotopic signature of the Elbrus snow cover and glacial ice. The sampling of precipitation was organized at Azau station, located at the foot of Elbrus at an altitude of 2300 m for the period from May 01.2019 to September 27.2021. The sampling was carried out once a day at 9:00 Moscow time. The air temperature was recorded at the meteorological station in the Terskol village (Roshydromet station No. 4334250). To study the main features of long-range air transport and possible sources of moisture, 5-day back trajectories were reconstructed using the NOAA HYSPLIT_4 trajectory model. The results showed that precipitation in the Elbrus region in winter was associated with the prevailing transfer from the Atlantic, in summer – with the predominance of transfer from the regions of Central Europe, the Mediterranean and Black Seas. The Mediterranean Sea in all seasons was the area from which the air and moisture were transferred to Elbrus. The values of δ18О and δ2Н of precipitation varied from 0.52 to −28.22‰ and from 16.3 to −224.1‰, respectively, revealing regular seasonality with high values of δ18О and δ2Н in summer and low in winter. The deuterium excess varied over a wide range from 24.8 to −14.6‰. All obtained values of δ18О and δ2Н were approximated by the equation δ2Н = 8δ18О + 7.06 (R2 = 0.98), which was close to the global meteoric water line. In general, for 2 years of observations, the relationship between the δ18О values of precipitation and the temperature of the surface air layer was expressed as 0.85‰/°С. Total mean absolute error in the reconstruction of air temperatures from the δ18О value of precipitation was 3.2°С due to objective reasons and also differences in meteorological conditions of two years of observations.

We consider the distribution of tropospheric ozone on the territory of Russia in 2022 using data from 33 stations located in different physical and geographical zones, as well as its vertical distribution from results of aircraft sensing. It was shown that measurements at all measurement sites exceeded the maximum permissible daily average concentrations, determined by the national hygienic standard. In some regions, the excess over the maximum permissible concentrations of the working zone and over the maximum one-time hourly average concentrations is recorded, so that the population should be broadly warned about the monitoring results and measures should be taken to reduce the level of ozone concentration in the surface air layer.

Ozone is one of the most toxic admixtures in the troposphere. Therefore, it is among the main pollutants and its concentration is monitored. This work represents an overview of continuous measurements of the ozone content in the troposphere on the territory of Russia throughout 2021 carried out on an initiative of scientific and educational institutions at 17 stations in different Russian regions. The monitoring results showed that the daily average ozone concentration exceeded the MPC d.a level during a major part of the year at all observation sites, and by a factor of two or even three at a number of stations. At six stations, concentrations in excess of the maximum permissible one-time concentration MPC m.o were recorded. This requires a more comprehensive analysis of the composition and concentration of ozone precurcors and the development of measures to reduce their emission into the atmosphere.

Nowadays, dried lakes have turned into important dust sources with serious environmental, climatic and socio-economic impacts. In this study, climatic, terrestrial and anthropogenic effects that caused desiccation of the Urmia Lake, NW Iran are investigated. The main objective is to assess the influence of climatic and regional factors against anthropogenic and local ones in the dryness of the lake during the last two decades. Annual temperature, precipitation and wind speed data measured at nearby meteorological stations, along with water discharge of eight main rivers flowing into the lake are analyzed. The results reveal that the main cause for turning Urmia into a dried lake bed was human interference, since climatic factors contributed positively but to a lesser degree, while terrestrial factors may also play a crucial role. Among anthropogenic interferences, the construction of a causeway had a weak effect in the lake's dryness, while construction of many river dams highly contributed to this disaster. Furthermore, four machine learning models showed that groundwater decline is also an important factor for lake's desiccation. Analysis of dusty days at stations in the Urmia Basin showed similar inter-annual and seasonal dust variability over the whole western Iran. This indicates that dust over the Urmia Basin is mainly affected by the regional dust activity, while the dried lake beds contribute to a lesser degree to the enhanced dust loading. The dominant wind flow is mostly southwesterly, carrying Urmia saline dust toward NE directions, affecting Tabriz city. Three main synoptic clusters, with dipole features consisted of high-pressure systems over Europe, Central Mediterranean and North Africa and low pressure over SW Asia, facilitated strong westerly winds from arid, desert areas of the Middle East toward the Urmia Basin during 118 dust storms in the region.

Рассматривается распределение тропосферного озона на территории России в 2022 г. по данным 33 станций, расположенных в разных физико-географических зонах, а также его вертикальное распределение по результатам самолетного зондирования. Показано, что во всех пунктах измерений превышались предельно допустимые среднесуточные концентрации, установленные отечественным гигиеническим нормативом. В отдельных регионах фиксируется превышение предельно допустимых концентраций рабочей зоны и максимальных разовых среднечасовых концентраций в сложившейся ситуации необходимо широко информировать население о результатах мониторинга и проводить мероприятия по снижению уровня концентрации озона в приземном слое воздуха. The work considers the distribution of tropospheric ozone in Russia in 2022 according to 33 stations located in different physical and geographical zones, as well as its vertical distribution according to the results of aircraft sensing. It was shown that ozone concentration stations the maximum permissible daily average concentrations established by the domestic hygienic standard at all exceed. In some regions, the maximum permissible concentrations of the working zone and the maximum one-time hourly average concentrations are exceeded. The current situation causes the need to widely inform the population about the monitoring results and develop environmental measures to reduce the level of ozone concentration in the surface air layer.

Based on the database of the elemental and ionic composition of the tropospheric aerosol according to the data of aircraft measurements in the south of Western Siberia (SWS) in 1997-2020, taking into account the synoptic information about the air masses (AM) prevailing on sounding days and the results of the trajectory analysis, two main trajectorysynoptic samples with cases of the influence of the Aral-Caspian arid region (ACAR) on the SWS and with days without such influence. The chemical components-references of the ACAR aerosol were revealed: silicon, strontium, chromium, silver and magnesium - in the elemental composition, and in the water-soluble fraction - halide anions (fluorides, bromides and chlorides), ammonium and sodium cations. Days with the influence of ACAR are characterized by a 1.5-2- fold increase in the number concentration of aerosol particles with a size of 0.6-4 μm, which is associated with an increase in the volumetric concentration of aerosol in the atmospheric layer of 0.5-7 km by 1.5 times.

С использованием спутниковых (NASA) измерений яркостной температуры поверхности Арктики с помощью российского алгоритма VASIA2 восстановлены ряды концентрации морского льда (КМЛ) в пяти основных проливах, Карские Ворота, Вилькицкого, Лаптева/Санникова, Лонга и Беринга, в период летне-осенней (июнь-ноябрь) навигации вдоль Северного морского пути (СМП) в 1988-2020 гг. Для указанных проливов и всех месяцев летне-осенней навигации получены оценки: средних КМЛ в 2001-2010 гг. и в 2011-2020 гг., линейных трендов среднемесячной КМЛ в 1996-2020 гг., сроков наступления безлёдных условий в XXI в., современных (для 2020 г.) вероятностей тяжёлых, средних и лёгких ледовых условий, а также оценки экстремальных КМЛ в 2001-2020 гг. и 1988-2000 гг.

The plots of monthly regional contribution to extreme positive and negative anomalies of surface air temperature in Moscow in 1949-2019 have been restored. Monthly large-scale atmospheric circulation patterns favoring superheated and supercooled air’s intrusions into the Moscow region in 1949-2019 were obtained. Drivers of supercooled air transfer in cold season are anticyclones centered over the Kola Peninsula, in warm season - cyclones centered over the middle and polar Urals. Transfer of superheated air in cold season is facilitated by cyclones centered over the south of the Scandinavian Peninsula, in the warm season - by anticyclones centered over middle Volga region.

Сравнивается степень влияния Арало-Каспийского аридного региона на территории России вдоль её южной границы, а также на страны ближнего и дальнего зарубежья по данным измерений метеорологической оптической дальности в 2000-2020 гг., аэрозольной оптической толщины (АОТ) грубодисперсного аэрозоля на станциях AERONET в последние два десятилетия и АОТ пылевого аэрозоля со спутника CALIPSO в 2006-2020 гг.