Near-surface Air Layer Research Articles

Nearsurface Air Layer Pollution with Micronic Dust Particles in Large-Scale Blasting in Open Pit Mining

Nearsurface Air Layer Pollution with Micronic Dust Particles in Large-Scale Blasting in Open Pit Mining

Nearsurface Air Layer Pollution with Micronic Dust Particles in Large-Scale Blasting in Open Pit Mining

Nearsurface Air Layer Pollution with Micronic Dust Particles in Large-Scale Blasting in Open Pit Mining

Исследование влагопоглощения авиационных углепластиков в условиях теплого влажного климата

Long-term moisture absorption of aeronautical carbon fiber reinforced plastic based on epoxide in conditions of warm humid climate is studied (city of Sochi). The phenomenon of cyclical stochastic fluctuation of moisture absorption of seasonal nature in samples, placed in open atmospheric stand of the climate platform, is established. Thermal-moisture characteristics of the air layer near the sample surface during insolation are examined. They determine the front surface overheating of the sample and the humidity gradient change of the near-surface air layer relative to meteorological data. The layer size, which is 6-8 mm from the sample surface, is found by direct measurements. It depends not only on the intensity of the insolation, but also on the convection and wind heat exchange with the surrounding atmosphere. During summer insolation, the maximum temperature of the sample front surface (Т) in open atmospheric stand reached 54,0oC, and the relative humidity (RH) in the near-surface layer did not exceed 12, 9 %. Regarding the atmospheric meteorological parameters, this indicates an overheating of the surface by 24,7o C and a decrease in the near-surface RH by 46, 1%. The obtained data exceed daily fluctuations of atmospheric parameters for T by 4 times and for RH by 3 times. The importance of the obtained results is determined by the fact that cyclic changes in the sample surface temperature result in aging of aeronautical carbon fiber- reinforced plastic. They contribute to the development of physical and chemical processes in the material and during the operation of products (25-30 years) they can significantly reduce their strength properties.

Radioactive Aerosols within Conditions of the New Safe Confinement in 2017–2020

The results of monitored behavior of radioactive aerosols within the conditions of the New Safe Confinement (NSC) in 2017–2020 are presented. Maximum “unorganized” flux of beta-emitting products of the Chornobyl accident from the Shelter object through the process openings and leakages of light roofing in the NSC basic volume observed in 2017 made 7.9 kBq/(m2 ∙day). Mean annual density of radionuclide deposition onto the light roofing during four years has been changing within the range of 1.7–2.2 kBq/(m2 ∙day). Over these years, mean annual volumetric activity of sum of long-lived beta-emitting nuclides coming in the “Bypass” system dropped from 0.84 to 0.17 Bq/m3 . Their carriers were aerosol particles with activity median aerodynamic diameter, mainly, from 4.3 to 10 μm. The data are given on radioactive contamination of near-surface air layer in the NSC basic volume.

Brief communication: Rare ambient saturation during drifting snow occurrences at a coastal location of East Antarctica

Abstract. Sublimation of snow particles during transport has been recognized as an important ablation process on the Antarctic ice sheet. The resulting increase in moisture content and cooling of the ambient air are thermodynamic negative feedbacks that both contribute to increase the relative humidity of the air, inhibiting further sublimation when saturation is reached. This self-limiting effect and the associated development of saturated near-surface air layers in drifting snow conditions have mainly been described through modelling studies and a few field observations. A set of meteorological data, including drifting snow mass fluxes and vertical profiles of relative humidity, collected at site D17 in coastal Adélie Land (East Antarctica) during 2013 is used to study the relationship between saturation of the near-surface atmosphere and the occurrence of drifting snow in a katabatic wind region that is among the most prone to snow transport by wind. Atmospheric moistening by the sublimation of the windborne snow particles generally results in a strong increase in relative humidity with the magnitude of drifting snow and a decrease in its vertical gradient, suggesting that windborne-snow sublimation can be an important contributor to the local near-surface moisture budget. Despite a high incidence of drifting snow at the measurement location (60.1 % of the time), saturation, when attained, is however most often limited to a thin air layer below 1 m above ground. The development of a near-surface saturated air layer up to the highest measurement level of 5.5 m is observed in only 8.2 % of the drifting snow occurrences or 6.3 % of the time and mainly occurs in strong wind speed and drift conditions. This relatively rare occurrence of ambient saturation is explained by the likely existence of moisture-removal mechanisms inherent to the katabatic and turbulent nature of the boundary-layer flow that weaken the negative feedback of windborne-snow sublimation. Such mechanisms, potentially quite active in katabatic-generated windborne-snow layers all over Antarctica, may be very important in understanding the surface mass and atmospheric moisture budgets of the ice sheet by enhancing windborne-snow sublimation.

Sulfur and Nitrogen Gases in the Vapor Streams from Ore Cyanidation Wastes at a Sharply Continental Climate, Western Siberia, Russia

The article presents the results of the study of the vapor streams from sulfide-containing tailings after gold mining by cyanidation (Ursk waste heaps, Kemerovo region, Russia). The gas survey of sulfur dioxide, dimethyl sulfide, dimethyl sulfoxide, carbon disulfide, and N-containing substances concentrations was carried out using a portable device GANK-4 on a series of profiles covering the waste heaps and the surrounding area with simultaneous measurement of temperatures in the air and soil. The concentration maps-schemes of the studied gases in the surface layer were constructed. The high positive correlation of gases between themselves is established, which indicates similar mechanisms of their formation. The electrical resistivity tomography determined the internal structure of the waste heap. Active “breathing” zones were identified in which the maximum fluctuations in the concentrations of sulfur, selenium, and nitrogen-containing compounds in the near-surface air layer were recorded. Such zones are marked with lower resistances in comparison with other areas on the geo-electric profiles. There is an inverse correlation between the resistivity of the tailings and its temperature and a direct correlation between the concentration of gas in the air and the temperature of the soil. High concentrations of CS2, the volatile gas compound of the second hazard class, were found in the concentrations that exceed 6–8 times the daily average norm. Further investigation of the mine tailings seasonal transformation with the production of toxic gases deserves special attention due to high environmental risks and poor knowledge of this problem. The oxidation of ore cyanidation wastes in summer and methylation in winter due to seasonal temperature fluctuation lead to production of gases of great concern including toxic СS2.

Black Carbon in Near-Surface Air in Pechora-Ilych Nature Reserve: Measurements and Sources

New data on the black carbon (BC) content in the atmosphere are obtained during year-round daily monitoring of BC concentration in the near-surface air layer in a hard-to-reach region of the northern Urals (on the territory of Pechora-Ilych Nature Reserve) with the time resolution of 1 day. Results are analyzed for the cold half-year (from October 2017 to March 2018), when only BC of anthropogenic origin is present in the atmosphere and no fire effect is possible. Average BC concentrations (plus or minus standard deviation) are (296 ± 172) and (175 ± 82) ng/m3 in the near-surface air of Yaksha settlement and outside it, respectively. Comparison of monthly average BC concentrations in the near-surface air with those estimated from satellite observations ( https://giovanni.gsfc.nasa.gov/giovanni/ ) shows a satisfactory agreement, serving as a cross-check and confirming the reliability of results. Trajectory analysis of long-range transport of air masses and BC for the region of Pechora-Ilych nature reserve made it possible to identify the main anthropogenic BC sources in the atmosphere at distances less than 500 km on industrial territories of the central Urals, areas of carbon-containing fuel production in Yamalo-Nenets and Khanty-Mansiysk Autonomous Districts, in the cities and settlements of Perm oblast, Udmurtia, and the Komi Republic.

Variability of the aerosol microstructure under the forest fire smoke effect retrieved from spectral characteristics of light extinction in the near-surface air layer and the atmospheric column

Variability of the aerosol microstructure under the forest fire smoke effect retrieved from spectral characteristics of light extinction in the near-surface air layer and the atmospheric column

Development of a Subcloud Layer over the Sea during a Cold Air Invasion

Evaporation and vertical moisture and heat transfer from the underlying surface are the basis of cloud formation. The situation when the coming relatively cold stably stratified air moves over a warm ocean is a typical problem in the development of a turbulent convective layer. The problem of cloud formation is also of scientific and practical interest. This paper considers the problems of the formation of a turbulent convective layer over a warmer ocean and the vertical distribution of relative humidity. The results of the theoretical model are compared with the data of observations of the development of the turbulent convective layer at low latitudes (in the Indian Ocean) and at higher latitudes (in autumn over Lake Michigan). Approximate equations describe well the dynamics of temperature and humidity of the layer as a function of the difference between the temperatures of the approaching and near-surface air layers. The theoretical results are compared with the data on measurements of the condensation heights obtained at the Novosibirsk Tolmachevo Airport. Some discrepancy between them is due to the unsteadiness measurement and the approximations adopted in the theoretical model.

Hyper-cooling in the nocturnal boundary layer: the Ramdas paradox

Characterizing the interaction between turbulence and radiative processes is necessary for understanding the nocturnal atmospheric boundary layer. The subtle nature of the interaction is exemplified in a phenomenon called the ‘Ramdas paradox’ or the ‘lifted temperature minimum’ (LTM), involving preferential cooling near the Earth's surface. The prevailing explanation for the LTM (the VSN model, Vasudeva Murthy et al (1993 Phil. Trans. R. Soc. A 344 183–206)) invokes radiative exchange in a homogeneous nocturnal atmosphere to predict a large cooling of the near-surface air layers. It is shown here that the cooling predicted by the VSN model is spurious, and that any preferential cooling can occur only in a heterogeneous atmosphere. The underlying error is fundamental, and occurs to varying degrees in a wide class of radiative models, in a flux-emissivity formulation, the VSN model being a prominent example. We, for the first time, propose the correct flux-emissivity formulation that eliminates spurious cooling. Results from field observations and laboratory experiments presented here, however, show that the near-surface radiative cooling is real; near-surface cooling rates can be orders of magnitude higher than values elsewhere in the boundary layer. The results presented include the dependence of the LTM on turbulence, the surface emissivity and the thermal inertia of the ground. It is proposed that aerosols provide the heterogeneity needed for the preferential cooling mechanism. Turbulence, by determining the aerosol concentration distribution over the relevant length scales, plays a key role in the phenomenon. Experimental evidence is presented to support this hypothesis.

Influence of bottom topography inhomogeneity on the near-surface air layer

A connection between processes in the deep-water zone and in the near-surface air layer is considered. Measurements were carried out under different meteorological conditions in the shallow-water zone and in the area of depth variation from 250 to 2500 m. It is found that the change in bottom topography results in a transformation of the flow field and surface-wave spectrum, which leads to a change in the structure of the near-surface air layer. Measurements showed that the structure of atmospheric turbulence varied in all cases of depth variation. Thus, variations in bottom topography can manifest themselves in characteristics of surface waves and near-surface atmospheric layer.

What can Be extracted from data on the concentrations of Be-10 and C-14 natural radionuclides?

Series of data on the concentrations of Be-10 radionuclides in Greenland and Antarctic ices and C-14 radionuclide in tree rings are compared with each other. The existence of substantial divergences between these data series is shown. The Be-10 and C-14 radionuclides are produced in the Earth atmosphere by cosmic rays. However, the comparison of the concentrations of these isotopes with data on the galactic cosmic-ray fluxes measured in stratospheric studies exhibits their weak correlation. At the same time, data on Be-10 and C-14 show a sufficiently strong correlation with global temperature variations of the near-surface air layer within the period of 1880–1986 for which these quantities were simultaneously measured. It is concluded that atmospheric processes noticeably affect the concentrations of Be-10 and C-14 atoms and that the time dependences of these concentrations carry information mainly on variable conditions of the atmosphere, in particular, the global temperature of the near-surface air layer. Thus, it seems to be unreasonable to use data on Be-10 and C-14 for reconstructing both galactic cosmic-ray fluxes and other characteristics of the solar activity in the past.

Sensible heat flux and local advection over a heterogeneous landscape at an Arctic tundra site during snowmelt

During snowmelt over a continuous snow cover, the vertical turbulent exchanges of sensible and latent energy are influenced by regional air-mass characteristics, which exert a strong control on air temperature. In high-latitude sites, the melting surface rapidly becomes heterogeneous, with patches of snow and snow-free areas. Local advection occurs when near-surface air layers are warmed due to sensible heal flux from the snow-free areas, with the resulting heat transferred horizontally to adjacent snowpatches. This advection greatly increases the rate of snowmelt along the leading edges of the snowpatches. In order to estimate correctly the average melt rates of the snowpatches and the bulk energy balance of the entire landscape, it is necessary to estimate the local advection component. To date, few studies have dealt with this problem. This paper reports results from an Arctic tundra site located approximately 55 km northeast of Inuvik, Northwest Territories, Canada. The importance of local advection is estimated by comparing the sensible heat flux of the snowpatches to estimates of sensible heat without local advection. This latter term is derived from a relationship between upper air temperature and sensible heat flux over a continuous snow cover. This work has important implications for developing models that correctly represent the cryosphere of tundra regions, and in developing appropriate scaling techniques for heterogeneous landscapes.

The pollution exchange between soil and the near-surface air layer through turbulent transfer, resuspension and dry deposition

The exchange of pollutants between the soil and the near-surface boundary layer is considered taking into account the effects of dry deposition, sedimentation and resuspension. The time taken to reach steady-state conditions has been evaluated. The exact solutions of conventional vertical turbulent diffusion with a given lower boundary condition have been derived and analysed.