The paper presents the results of experimental measurements of the aerosols mass concentration PM2.5 and PM10 at the Boyarsky station in May-September 2022. According to the results of measurements and model calculations by Copernicus (CAMS) and Ventusky (SILAM), the seasonal variability of PM2.5 and PM10 aerosol in the atmosphere of Lake Baikal is revealed. The highest concentrations of PM2.5 and PM10 were found in spring (40±18 and 81±34 μg/m3) and summer (20±16 and 26±20 μg/m3), the lowest in autumn (10±5 and 16±11 μg/m3). During the smoke drift, a significant increase in the concentrations of aerosol fractions PM10, PM2.5 and gas impurities NO2, SO2 was noted.
The results of monitoring of the concentrations of gas impurities (SO2, NO, NO2, O3), aerosol particles of different fractions (ultrafine and submicron aerosols) in the coastal zone of the Lake Baikal (Boyarsky station) in different seasons of the year (spring, summer, autumn) during the experiments of 2022 are presented. It was revealed that in the spring months, the highest average daily concentrations of ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), and the number concentration of nanometer-sized particles are observed compared to other seasons. In the summer months, the proportion of particles of the submicron size range increases, due to an increase in the contribution of not only anthropogenic sources of emissions, but also natural sources (wildfires) during this period of the year.
The results of experimental studies of the spatial and temporal variability of small gas impurities, the total number concentration of the ultrafine particle in the size range from 5 to 200 nm (UFA) and the submicron aerosols (SMA) – from 0.2 to 1 μm during route ship measurements in the water area of Lake Baikal in the summer of 2022. The report analyzes the features of the distribution of ozone, nitrogen oxides, sulfur dioxide and the total number concentration of aerosol in the lake area, depending on the circulation of air masses, synoptic conditions and anthropogenic outflows during the observation period.
The study characteristics of gas exchange processes (the flux (F) and velocity (Vd) of the dry deposition of ozone) on different types of vegetation (grasslands, forest) in the Baikal region are presented. Investigations were carried out on the basis of micrometeorological models of deposition of gas impurities. Based on proven calculation methods and with experimental data, the quantitative estimates of the flux and velocity of the dry deposition of ozone in the forest environment and grasslands vegetation Baikal region were obtained. The quantitative estimates of the fluxes and velocity of dry deposition of ozone to soil vegetation and in the forest show a higher absorptive capacity of forests compared to soil vegetation.
The results of the experimental study of the concentration of small gas impurities and aerosol dispersion composition in the atmosphere under Lake Baikal in September 2021 are presented. Almost all the route observed short bursts in the concentration of gas components and aerosol due to the proximity to the continental sources of emissions. In spite of unfavorable weather conditions, a high share of anthropogenic components in the atmosphere was observed in the area of Listvyanka port. There was a sharp increase in the concentration of ozone and sulfur dioxide in the area of Aya Bay in the night hours due to displacement and destruction of the anticyclone in the adjacent coastal zone.
The results of measurements of the aerosol size distributions and number concentrations in the atmosphere of the South-Eastern coast of Lake Baikal (“Boyarsky” station) for the April, July and September 2021 are presented. Atmospheric aerosol measurements were carried out in a wide range of sizes from 5 nm to 1μm. To analyze the processes of aerosol formation and transformation, the range under consideration was divided into following mode: nucleation mode, Aitken mode and accumulation mode. The maximum concentration of the Aitken mode was prevailed in all seasons, which account for more than 63%. The highest concentrations of the nucleation mode are observed in the spring period, the share of which is 29% of the total content of the number aerosol concentration.
The results of the experimental study of the spatial-temporal variability of the counting concentration of the highly dispersed (VDA) and submicron fraction (SMA) of aerosol in the atmosphere of the Baikal region are presented. A comparative analysis of the features of the distribution of the aerosol dispersion composition at the continental and coastal stations and during route measurements in the water area of Lake Baikal is carried out. The diurnal variations of the counting concentration of the highly dispersed (VDA) and submicron fraction (SMA) of aerosol have common patterns: the maximum diurnal concentrations are more often manifested in the morning, afternoon and evening hours. The general feature of the diurnal variations of the counting concentration of VDA and SMA is an increase in the concentration in the afternoon and evening hours. The average concentrations of VDA and SMA during of all period of measurements are equal: for suburban station of Ulan-Ude 4120 and 122 particles/cm3, respectively; for station “Boyarsky” 2646 particles/cm3, 43 particles/cm3; for water area of Lake Baikal 3055 particles/cm3 and 98 particles/cm3.
The results of the study of the spatial-temporal variability of the counting concentration of the highly dispersed (VDA) and submicron fraction (SMA) of aerosol, small gas impurities (sulfur dioxide SO2, nitrogen dioxide NO2, ozone O3) over water area of Lake Baikal during the expedition on board the research vessel "Academician V. A. Koptyug" from July 29 to August 11, 2020 are presented. The average daily concentration of ozone over the lake was 67 μg/m3, sulfur dioxide - 7 μg/m3. The highest concentrations of small gas impurities and aerosol particles were observed in areas with a high anthropogenic load and in areas under the influence of forest fires. The average values of the counting aerosol concentration of VDA fraction and SMA in the lake area during were 3055 particles/cm3 and 98 particles/cm3, respectively.
The experimental study of the flux and rate of the dry deposition of small gaseous impurities on different types of vegetation in the Baikal region are presented. Based on the eddy covariance method and the flux gradient methods (including the aerodynamic gradient method (AGM), the modified Bowen method (MBR) and modified gradient method (MGM)) and with experimental data, the quantitative estimates of the fluxes and dry deposition velocity of ozone on the underlying surface were obtained for different environments (grasslands, forest). The average values of the dry deposition velocity of ozone (Vd) were equal to 0.37 cm/s at night (0–3 h) and 0.91 cm/s during daytime hours (12–18 h). The ozone flux (F) was 0.24 μg m–2 s–1 at night and 0.72 μg m–2 s–1 in the afternoon. The quantitative estimates of Vd and F on vegetation and in the forest show a higher absorptive capacity of forests compared to soil vegetation.
The results of experimental studies of small gas impurities in the atmosphere above Lake Baikal in July-August 2019 from the board of the science research vessel “Academic V.A. Koptyug". The features of ozone distribution, nitrogen oxides, and sulfur dioxide over the lake water area are analyzed depending on the circulation of air masses, synoptic conditions, the pyrogenic situation, and anthropogenic drifts during the observation period.
The analysis of aerosol optical thickness variations of Tory atmosphere from 2012-2019 using the CE-318 sun photometer (AERONET) is carried out. It is revealed that station Tory is subject to strong smoke from forest fires in the spring-summer period, which largely determine the spectral course of aerosol optical depth. The distribution of aerosol particles in size showed that in the spring and summer months the proportion of subfraction aerosol is high. In addition, the paper presents the results of a comparative analysis of the ultrafine aerosol obtained using an aerosol diffusion spectrometer in the spring-summer period in Lake Baikal coastal zone.
The results of experimental studies of the daily variability of surface ozone concentration (O3) in the atmosphere of the arid territory of Mongolia, obtained during scientific expeditions for the period 2005-2014 at the Sainshand station, are presented. Variations of hourly average concentrations of the O3 changed from 70 to 126 μg m-3.The daily variation of surface ozone concentration has minimal values in the morning during sunrise, and then there is an increase in ozone concentration in the daytime. The average amplitude of diurnal variations of O3 was 56 μg m-3.The maximum values of O3 in the daily dynamic were observed in 2014, and the minimum values in 2007.The factors leading to increased surface ozone content and their relationship to meteorological and turbulent characteristics of the atmosphere are analyzed. A special mode of behavior of surface ozone, characterized by its day and night increase in daily changes, was revealed.
The results of measurements of surface ozone concentration in a forest near the coastal zone of Lake Baikal were analyzed. Using a micrometeorological models the characteristics of gas exchange processes (fluxes and rates of dry deposition) between the atmosphere and forest vegetation are studied. A new modified micrometeorological gradient method has been developed and used to quantify the dry deposition of ozone over the forest canopy using concentration gradients at levels above and below the top of the forest canopy. Based on the approved calculation method and experimental data the quantitative estimates of flows and rates of dry ozone deposition in the forest environment in Baikal region were obtained.
An analysis of measurement data of surface ozone and nitrogen oxides concentrations near the coastal zone of Lake Baikal is carried out. Features of vertical distribution of surface ozone and its diurnal variations are revealed. The air flow changing play an important role in the diurnal variations of ozone and other small gas impurities under the conditions of breeze circulations. The air flow changing substantially affect to the transport and dispersion of atmospheric impurities in the region. Features of structure and dynamic of meteorological processes in an atmosphere of coastal zone of Lake Baikal are noted.
The paper presents the results of studies of air mass and smoke aerosol transport using the HYSPLIT, NAAPS models and data of remote sensing CALIPSO during the forest fires in 2016 in Baikal region. In June 2016 the homogeneous filling of the atmosphere by smoke aerosol over the Baikal region up to 2 km was observed. It is revealed that in the spectra of particle size distribution the large particles of the submicron aerosol fraction with a diameter exceeding 200 nm are observed, typical for smoke particles. The results of trajectories calculation have shown that in June influence of local fire on air quality in Ulan-Ude was observed under the general northwest transport of a smoke aerosol, in July downwind was mainly from the Irkutsk, Krasnoyarsk and the Yamalo-Nenets regions.
The paper discusses the results of experimental studies of chemical, microphysical and optical properties of atmospheric aerosol in different natural and climatic conditions of Mongolia. The main factor in the formation of the component composition of aerosols are anthropogenic emissions, whose proportion in the urban atmosphere (Ulan-Bator, Sukhbaatar) is significantly higher than at stations in arid regions where regional sources of emissions are associated with mining enterprises, road transport and terrigenous dust. The data of long-term observations AERONET at the station Dalanzadgad were used for analyze of the seasonal, annual variations of AOD in the Gobi Desert. It is established that high transparency of the atmosphere is observed (τ0.5=0.09) with a maximum in spring and summer (τ0.5=0.15) and a minimum in winter (τ0.5=0.04).
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