Sergey Beresnev

Photophoresis of a spherical particle in a rarefied gas

On the basis of the linearized gas‐kinetic model equations solution (the BGK and the S model), a force affecting a unilaterally illuminated spherical particle in a rarefied gas is calculated. Numerical calculations of the photophoretic force and the particle motion velocity are carried out for the whole range of Knudsen numbers taking into account the particle’s thermophysical, optical, and accommodation properties. The results obtained are compared to the known theoretical and experimental data.

Thermophoresis of a spherical particle in a rarefied gas: Numerical analysis based on the model kinetic equations

A kinetic theory for the thermophoretic force and velocity of a spherical particle in a rarefied gas is presented. The analysis is carried out on the basis of the linearized Bhatnagar–Gross–Krook (BGK) and S model [Fluid Dyn. 3, 95 (1968)] kinetic equations. The integral‐moment method of solution for arbitrary values of Knudsen number is employed. The set of integral moment equations was solved by the Bubnov–Galerkin method. The possibility of arbitrary energy and tangential momentum accommodation of gas molecules on the particle surface is taken into account in the boundary condition. The particle–gas heat conductivity ratio Λ is assumed to be arbitrary. The results obtained are compared to the available theoretical and experimental data.

Photophoresis of aerosol particles

Abstract On the basis of the linearized gas-kinetic equation solution a force affecting a unilaterally-illuminated aerosol particle is calculated. Numerical calculations of the photophoretic force and the particle velocity are carried out for the whole range of Knudsen numbers taking into account the particles thermophysical, optical and accommodation properties. The results obtained are compared to the known theoretical and experimental data.

Characteristics of the annual behavior of the spectral aerosol optical depth of the atmosphere under conditions of Siberia

Based on multiyear observations in Tomsk (since 1995, in the wavelength range 0.37–4 μm) and other regions of the Asian part of Russia (2003–2008), we determined the specific features of the annual behavior of the characteristics of the spectral aerosol optical depth (AOD) of the atmosphere. It is shown that AOD peaks are observed in April (0.19 in the region of 0.5 μm) and July, a local minimum in June (less than 0.16), and minimum values in the fall (0.12). The seasonal variations of the Angström selectivity exponent are characterized by elevated values in the warm period (maximum in July) and low values in winter. The closeness of the seasonal variations of aerosol turbidity in three Siberian regions is noted, and the Siberia mean annual behavior of atmospheric AOD characteristics is suggested. The average values of the aerosol optical and microphysical characteristics of the atmospheric depth for characteristic periods of intraannual AOD variations are presented.

Sensing HDO/H2O in the Ural’s atmosphere using ground-based measurements of IR solar radiation with a high spectral resolution

The Ural Atmospheric Fourier Station (UAFS) based on a Bruker IFS-125M Fourier spectrometer conjugated with an A547N automated solar tracker is described. The UAFS is located in the forest area (57.038°N; 59.545°E) and is intended for trace gas monitoring in the background atmosphere. The examples of solar-radiation near-IR atmospheric transmittance spectra measured with a high spectral resolution are presented, as well as the first results of retrieval of the heavy water fraction in the Ural atmosphere.

Role of gas and aerosol components of the atmosphere in the model of greenhouse explosion

Within the model of an equivalent grey atmosphere, the analysis of different mechanisms of negative feedback in the heat balance of the Earth’s surface, forming the stability of its current temperature regime and the only positive feedback mechanism which is able to lead to stability loss and transition to more hot condition, as on Venus, has been carried out. The role of the main greenhouse gases such as CO2, H2O, CH4, and cloudy aerosol in the positive feedback mechanism, as well as evaporation, photosynthesis, and cloud cover in the negative feedback mechanism have been characterized. The criticality of the heat balance in relation to the growth rate of the planetary albedo with an increase in the temperature of the Earth’s surface has been elicited. Above the Earth’s surface, the current state can be the only stationary and globally stable one in the temperature range of >288 K.

On the consideration of the averaged vertical wind in problems of stratospheric aerosol transport

The influence of the averaged vertical wind on the transport of stratospheric aerosol has been analyzed with the use of the database of the GCM UKMO assimilated model for 1993–2006. With the problem regarding the action of a permanent source of particles near the stratopause taken as an example, it is shown that if the action of the averaged vertical component is taken into account along with the gravitational sedimentation and turbulent diffusion, the standard vertical profiles of the relative concentration of particles change cardinally. The results are presented for the levitation heights of particles of different densities and sizes in the stratosphere under the action of gravity and wind pressure.