Aerosol nanoparticles play an active role in heterogeneous processes which change the optical and physicochemical properties of the atmosphere and the state of ecosystems and climate. Aerosol generation conditions, its geographical and seasonal features affect the microphysical characteristics of ultrafine aerosol. The work considers the first results of summer field observations of the microphysical characteristics of ultrafine aerosol particles in the near-surface air layer in the dry steppe zone of southern Russia in 2021 and 2022. Taking into account the synoptic and meteorological conditions, the daily variations in the concentration and size distribution of ultrafine aerosols (nucleation and Aitken modes and a transient subfraction) are studied, as well as their short-term variability. The permanent presence of Aitken particles at any time of a day and under any meteorological conditions is ascertained. Minimal concentrations of nucleation particles and Aitken particles are detected at night and in the early morning. The nucleation particle generation rate is typically the highest in the morning hours, when photochemical processes are active; this causes the morning maxima of concentrations of nucleation and Aitken particles. The concentration of transient subfraction particles increases during the nighttime. The features of the short-period variability of ultrafine aerosols are studied taking into account the general dynamics of daily aerosol generation and subsequent particle growth in the atmosphere, as well as through comparison with observations in other regions of the world. The results can be used for the study of the atmospheric composition and in chemical transport models to clarify the contribution of aerosols to the direct and indirect radiative effect and to climate change processes.

Results of experimental studies of aerosol in the surface air layer in the southeastern part of the Crimean Peninsula at the background environmental monitoring Vyazemsky Karadag Scientific Station from March 21 to June 17, 2020, are presented. The daily average mass concentration of aerosol ranged from 3 to 35 μg/m 3 over the measurement period, with an average value of 13 μg/m 3 . The exception are high concentrations during the episode of March 25–27, 2020 (48, 195, and 49 μg/m 3 , respectively), when an extreme eastward transfer from sources in Kazakhstan (a dust storm in the region of the Aral Sea) through Kalmykia to the Crimea took place. Accounting this episode, the daily average mass concentration of aerosol was 16 μg/m 3 . Days with different directions of airmass arrival and days with the highest daily average mass concentrations of aerosol are distinguished out of 89 observation days. For this set (31 samples), the concentrations of 64 chemical elements in the samples are determined. Accumulation of chemical elements in soil and in aerosol particles is estimated; the clarkes of concentrations of chemical elements in soil, aerosol concentration coefficients, and enrichment factors of chemical elements in aerosols are calculated. The dependences of the mass concentration, size distribution, and elemental composition of the surface aerosol on long-range aerosol transport are considered.

The effect of the emergence of quasi-periodic oscillations of particle (with size >50 mсm) concentrations in the saltation flow has been detected in similar arid conditions in desertified areas: (1) using high-speed video in Astrakhan region (2009); (2) by acoustic method in the Republic of Kalmykia (2021). During the field experiments were revealed characteristic low frequencies (<50 Hz), which is associated with the peculiarities of the microrelief shape. More high frequences (>50 Hz) have been observed also. The appearance of these frequencies is determined by changes in the saltation cycle in heterogeneous topography. Such processes is simulated in a numerical experiment using the OpenFoam package. There are demonstrated the characteristic frequencies of changes in the number of particles (from 10 to 200 Hz) in the saltation flow over the surface ledge of the ripple type. Numerical experiments include analysis of frequency characteristics of particle concentration changes in the flow behind the ledge. Spectral analysis of data of numerical realizations of the saltation flow at variation of boundary parameters and height of the obstacle shows that the characteristic frequency or frequencies change and are close to those observed in the experiment. Input parameters such a models can be adjusted with such analysis.

We analyzed multiyear (2007–2021) complex experimental studies of microphysical parameters, mass concentration, and elemental composition of aerosol particles in the near-surface atmospheric layer of semiarid zones in the south of European Russia. Background values of the daily average mass concentration of near-surface aerosols in desertified areas of Kalmykia and the dry-steppe zone of Rostov oblast for the hot summer period are found to be 125 and 34 μg/m3, respectively. The particle size distribution functions specific for atmospheric aerosols of the south of European Russia, are determined. An interrelation is found between the particle emission from the surface to the atmosphere and the main atmospheric processes. Long-term variations in elemental composition of near-surface aerosol are studied. Minor variations are identified in the mass concentrations of Cd, Hg, and Cu in the composition of aerosol particles in Rostov oblast. The elemental composition of Kalmykia aerosols stronger varies in terms of the contents of both natural and technogenic elements, mainly of chemical elements of salt balance and heavy metals. It is shown that most elements are weakly accumulated in aerosols, and their differentiation is heavier dependent on the mosaic character of the underlying surface. The multiyear period under study is characterized by the tendency of removing the harmful admixtures from the atmosphere of desertified territories in the south of European Russia due to reducing the climate aridization and mitigating the anthropogenic effect.

In-situ knowledge on characteristics of mineral aerosols is important for weather and climate prediction models, particularly for modeling such processes as the entrainment, transport and deposition of aerosols. However, field measurements of the dust emission flux, dust size distribution and its chemical composition under realistic wind conditions remain rare. In this study, we present experimental data over annual expeditions in the arid and semi-arid zones of the Caspian Lowland Desert (Kalmykia, south of Russia); we evaluate characteristics of mineral aerosol concentration and fluxes, estimate its chemical composition and calculate its long-distance transport characteristics. The mass concentration in different years ranges from several tens to several hundred of μg m−3. The significant influence of wind velocity on the value of mass and counting concentration and on the proposed entrainment mechanisms is confirmed. An increased content of anthropogenic elements (S, Sn, Pb, Bi, Mo, Ag, Cd, Hg, etc.), which is characteristic for all observation points in the south of the European Russia, is found. The trajectory analysis show that long-range air particles transport from the Caspian Lowland Desert to the central regions of European Russia tends to increase in the recent decades.

In this paper, microparticle size distributions due to the wind direction - frontal and tangential in respect to the prevailing orientation of the dune crests are analyzed using field measurement data obtained during the 2010–2020 summer seasons in the arid conditions of the Near Caspian Lowland (Kalmykia, Russia). A smaller number of coarse-fraction microparticles (2–5 μm) and a larger number of fine-fraction microparticles (0.2–2 μm) are observed for the frontal wind direction in comparison with data for the tangential direction under similar conditions. The concentration of microparticles decreases for the frontal wind direction and increases for the tangential wind direction with the increase in friction dynamic velocity. Dust aerosol generation is associated with the movement of large particles near the surface by means of saltation or rolling (movement near the surface). The sizes of the generated microparticles are related to the momentum transferred to the particles in the layer. Concentrations of the fine fraction microparticles are associated with the presence of secondary aeolian structures on the surface of the windward slope and the relative change in the slope angle of inclination under the wind of different directions. This fraction generation due to shaking is more likely to occur when large particles move near the surface. The coarse-fraction concentrations are determined by the chipping processes that occur when a saltating particle blown from the top of the dune falls to the surface. When the wind direction is tangential and large irregularly shaped particles from the accumulation zone on the leeward slope are involved, the air circulation over the leeward slope weakens and the chipping processes intensify. The analytical derivation of the microparticle size distribution function and the comparison with field measurement data makes it possible to assess these effects in relation to the variation of angles of the aeolian-structure surface inclination and of particle velocities, which occur when the wind veers.

As an index of interannual climatic variability of the atmosphere, it is proposed to calculate the weighted average over the hemisphere area (to the pole from latitude 20°) of the vertical helicity flux across the upper boundary of the planetary boundary layer, which is determined by the product of the Coriolis parameter and the square of the wind speed at this boundary. In practical calculations, the data of reanalyses ERA-Interim and ERA-20C on the wind speed at the isobaric level of 850 hPa were used. The statistical distribution of the Earth’s surface area on the helicity flux values, as well as the informational entropy of this distribution, are calculated. It is shown that the introduced index usefully characterizes the interannual climate variability of the atmosphere in both hemispheres.

It is shown theoretically that the tendency of the height of the isobaric surface of 1000 hPa is proportional to the integral helicity of the geostrophic flow. This result is confirmed by calculations.

The results of experimental studies of the microphysical parameters of aerosol particles in the surface layer of the atmosphere of southeastern Crimea, performed in September 2018 - June 2019 at the background environmental monitoring station (BEMS) of the T.I. Vyazemsky Karadag Scientific Station. The dispersed composition and counting concentration of aerosol particles in the range of 0.15 -5 µm are determined. The mass concentration of aerosol PM5 particles ranged from 5 to 80 mg /m3 . An elemental composition analysis of aerosols taken on filters during primary measurements was performed.

— An investigation into mesoscale roll circulation and its transport characteristics in the atmospheric boundary layer (ABL) is carried out. The case study of July 28, 2007, in Kalmykia, monitored during an expedition from the Obukhov Institute of Atmospheric Physics, is considered using the WRF-ARW model. The development of circulation with considerable asymmetry in the positive and negative components of the velocity field and helicity is recorded. The quasi-2D roll structures are characterized by an intensification of the dust capture and accumulation from the underlying terrain and, along with intensive vortices with a vertical axis, are a significant source of atmospheric impurities. Captured finely dispersed aerosols can be transported at long distances and form aerosol layers.

A new informative and evident criterion for estimating the integral helicity is introduced - the gradient of integral helicity. On the example of a convective storm in Moscow on May 29, 2017, its prognostic property is shown (lead time is 12 hours). Its applicability as a prognostic indicator of adverse and dangerous weather phenomena is shown.

As an index of the general atmospheric circulation over the hemisphere, it is proposed to calculate the hemisphere-area-averaged (poleward of the latitude 20°) product of the Coriolis parameter by the wind velocity squared at the upper boundary of the planetary boundary layer. In practical calculations, data on the wind velocity at an isobaric level of 850 hPa were used. Control calculations for the 900 hPa level gave similar results. It is shown that the index introduced adequately characterizes the seasonal and interannual variability of the general atmospheric circulation over both hemispheres.

ДИНАМИЧЕСКАЯ ЗАДАЧА ТЕРМОЭЛЕКТРОУПРУГОСТИДЛЯ ФУНКЦИОНАЛЬНО-ГРАДИЕНТНОГО СЛОЯ А.О.Ватульян 1,2 , С.А.Нестеров 21 Южный федеральный университет, Ростов-на-Дону, Российская Федерация 2 Южный математический институт ВНЦ РАН, Владикавказ, Российская Федерация Приведена общая постановка задачи движения неоднородного термоэлектроупругого тела.Требуется определить наведенный в результате пироэффекта потенциал, возникающий на поверхности материала из пьезокерамики класса 6 mm.В качестве примера рассмотрена задача теплового удара по функционально-градиентному слою.При этом одна плоскость слоя заземлена, а на другой, в силу пироэффекта, наводится электрический потенциал.Осуществляется обезразмеривание начально-краевой задачи термоэлектроупругости, в результате которого выделяются параметры связанности.Исключение из постановки электрического потенциала позволяет преобразовать задачу термоэлектроупругости в задачу термоупругости с модифицированными коэффициентами.После применения к полученной задаче преобразования Лапласа задача термоупругости записывается в трансформантах, а затем сводится к системе интегральных уравнений Фредгольма 2-го рода.Система интегральных уравнений решается численно методом коллокаций с использованием квадратурной формулы трапеций.Оригиналы решений находятся на основе теория вычетов.На примере однородного слоя, изготовленного из титаната бария, проведено сравнение результатов численного и аналитического решений.Изучена связь характера наведенного потенциала с наиболее распространенными на практике типами тепловой нагрузки.Выяснено, как параметр дискретизации системы интегральных уравнений Фредгольма 2-го рода и разрядность чисел, которые задаются компьютеру, отражаются на точности численного решения.Исследована зависимость наведенного потенциала от распределения неоднородности в классах степенных и экспоненциальных функций.Выяснено, что вид законов распределения неоднородности коэффициента теплопроводности и удельной теплоемкости существенно влияет на форму наведенного потенциала.Показано, что вид законов распределения неоднородности модуля упругости, плотности материала и коэффициента температурного напряжения на форме наведенного потенциала не сказывается.Установленные результаты

Variations in the surface aerosol over the arid steppe zone of Southern Russia have been measured. The parameters of atmospheric aerosol (mass concentration, both dispersed and elemental compositions) and meteorological parameters were measured in Tsimlaynsk raion (Rostov oblast). The chemical composition of aerosol particles in the atmospheric surface layer has been determined, and the coefficients of enrichment of elements with respect to clarkes in the Earth’s crust have been calculated. It is shown that, in summer, arid aerosols are transported from both alkaline and sandy soils of Kalmykia to the air basin over the observation zone. Aerosol particles in the surface air layer over this region have been found to contain the products of combustion of oil, coal, and ethylized fuel. These combustion products make a small contribution to the total mass concentration of atmospheric aerosol; however, they are most hazardous to the health of people because of their sizes and heavy-metal contents. A high concentration of submicron sulfur-containing aerosol particles of chemocondensation nature has been recorded. Sources of aerosol of both natural and anthropogenic origins in southern Russia are discussed.

This chapter considers specific atmospheric pollution problems in Siberia, the current state of studies and strategic activities, and peculiarities of Siberian environmental protection problems, risk assessment, and tendencies in atmospheric pollution in Siberia, including health-affecting pollutants, greenhouse gases, aerosols, etc. The chapter does not presume to cover all the aspects of atmospheric pollution in Siberia. Its main focus is a short general overview of the existing problems of airborne pollution in Siberia and methodological aspects of air pollution impact assessments followed by several examples of such studies for Siberia. In particular, the following issues are described: (1) sources and characteristics of air pollution in Siberia, (2) air quality and atmospheric composition characterization, (3) assessment of airborne pollution in Siberia from air and space, (4) methodology and models for air pollution assessment on different scales, and (5) case studies of long-range atmospheric transport of heavy metals from industries of the Ural and Norilsk regions.