Victor N. Uzhegov

Testing the algorithms for taking into account relative humidity of air in the model of optical characteristics of absorbing aerosol

The paper presents the results of modeling of the aerosol optical characteristics taking into account the effect of relative humidity of air. Two algorithms were applied: humidification by the Hanel formula with the same parameter of condensation activity for all particles and introducing the dependence of aerosol hygroscopic properties on the particle size. The results of calculations are compared with the data of field measurements.

Comparison of the results of inversion of the spectral aerosol extinction coefficients and angular dependences of aerosol scattering

An array of spectral aerosol extinction coefficients is calculated from measurements of the spectral transparency of the atmosphere on a 1 km long horizontal path in 10 regions of the wavelength range 0.5 – 4 μm. An array of angular dependences of the aerosol scattering coefficients in the angular range 1.2 – 15° is obtained by means of an aureole photometer with closed scattering volume. Measurements were carried out under conditions of smoky atmosphere. Inverse problem was solved for two empirical data arrays obtained synchronously (200 realizations) and the aerosol particle cross section size distributions were calculated. It is shown that the results of two experiments are in quite good agreement in the particle size range from 0.18 to 1.8 μm. Objective. Determination of the aerosol particle size range, in which the results of aerosol monitoring by two instrumentation complexes are most representative. Method for solving the problem. The inverse problem was solved for two empirical data arrays: a) spectral aerosol extinction coefficients βext(λ) in the wavelength range 0.5 – 3.9 μm; b) angular dependences of the aerosol scattering coefficients βsct(φ) in the angular range Φ = 1.2 – 15° at the wavelength of 650 nm. The arrays βext(λ) and βsct(φ) were obtained in synchronous measurements by means of two independent instrumentation complexes [1,2]. In order to obtain the aerosol particle cross-section size distribution dS/dr, the inverse problem was solved using the algorithms [3-5]. The spectral dependence of the optical constants of aerosol particles was determined from the empirical data [6, 7]. Finally, two arrays of distributions dS/dr corresponding to the initial experiments data βext(λ) and βsct(φ) were calculated.

Seasonal variability of the aerosol absorption and scattering properties

An array of atmospheric aerosol optical characteristics is obtained from synchronous measurements on a long nearground path and in a local volume of air. The algorithm of statistical comparison of the data obtained is modernized. The spectral dependence of the single scattering albedo in the wavelength range 0.45 to 3.9 μm is calculated. Non-monotonic increase of albedo with wavelength is observed. Seasonal variations of albedo are estimated. Minimum values of albedo are observed in April and October, and maximum values are in July.

A technique for estimation of the aerosol optical constants and microphysical parameters from the data of scattering and extinction in visible and near IR wavelength range

When solving the inverse problem for the data measured with nephelometer in the visible wavelength range, the complex refractive index of aerosol particles is determined with an accuracy up to n–κ. Joint analysis of the scattering and extinction coefficients allows to obtain n and κ separately and to extend the range of particle sizes where the size distribution function is retrieved reliably. Estimates of the errors in determining n and κ, as well as the sensitivity of the measured parameters and to particles of different sizes are presented.

Empirical algorithm for estimation of the optical constants of absorbing aerosol

A technique is proposed for statistical estimation of the complex refractive index of absorbing aerosol using the data of field measurements of the optical characteristics of near-ground aerosol. The initial sub-array (165 realizations) of the refractive n(0.52) and absorption κ(0.52) indices of particulate matter is obtained from solution of the inverse problem for the wavelength of 0.52 μm. correlations of the obtained values n(0.52) and κ(0.52) with the optical parameters measured at the long atmospheric path and in the local volume are revealed. Iterative algorithm for estimation of the foregoing values separately for submicrometer and coarse aerosol is proposed. The errors in retrieval of the values n(0.52) and κ(0.52) are determined, they are δn=0,035 and δκ=0,016, respectively.

Comprehensive study of optical properties of natural smoke aerosols in july 2012 in tomsk

Was compared to the measured spectral aerosol extinction coefficients βa(λ) (λ: 0.5 - 3.9 μm) with coefficients directional light scattering βS(θ) (λ = 0.53 μm, θ: 1-45 °) and with mass concentration of the absorbing material in aerosol particles MBC. Measurements of optical and meteorological parameters were performed under conditions of forest fire smokes in July 2012 (706 realizations). It is shown that the magnitude of the aerosol attenuation of visible and infrared radiation can be estimated with certain accuracy, by measuring the light scattering parameters in a local volume. For dense fumes βa (0.55)< 1 km -1 was estimated single scattering albedo, which amounted to 97 - 98% in the visible region of the spectrum.

Extinction and scattering of optical radiation under smoke and clean conditions

A comparison of the measured spectral aerosol extinction coefficients βa(λ) and scattering coefficients directed βS(θ). Coefficients βa(λ) were obtained from measurements of atmospheric transmission on horizontal path length of 1 km for wavelengths from 0.45 to 3.9 microns. Scattering coefficients βS (θ) were measured in the angular range from 1 to 15 ° at a wavelength of 0.53 μm. The data were obtained under conditions of forest fire smokes in July 2012 and in clean conditions in April 2013 (706 and 204 realizations, respectively). Under clean conditions, 82% of variations of the extinction of radiation in the whole wavelength range are caused by variability of coarse aerosol, and 98% of variations under smoke conditions are related to submicrometer particles.

Aerosol and atmospheric electricity

It is well known that the range of scientific interests of Kirill Kondratyev was very wide. It is sufficient to say that in the period 2001–2006 he published about 20 reviews in the journal Atmospheric and Ocean Optics covering different problems of atmospheric opties. In particular, a significant part of the material in these reviews is devoted to the problems of aerosol generation, the spatio-temporal variability of aerosols in the atmosphere under the influence of different factors, and the role of acrosols as a climate-forcing component of the atmosphere.

Assessment of the effect of random and regular factors on the variability of the optical-physical state of near-ground haze

The paper is devoted to consideration of the relative effect of random and regular geophysical factors on the mechanism of formation of the disperse composition of near-ground haze. More than one thousand realizations of the aerosol extinction spectra measured on a horizontal near-ground path nearby Tomsk were attracted to the analysis. The parameters of theoretical and experimental statistical ensembles were compared. Their properties were presented in the form of expansion in terms of orthonormalized system of eigenvectors of the autocorrelation matrix. The data are obtained which characterize the peculiarites fo the change of the fraction composition of the near-ground haze at passing from summer to autumn.

Investigation of seasonal and diurnal dynamics of aerosol extinction in visible and IR wavelength ranges

Statistical characteristics of the variations of the spectral aerosol extinction coefficients α(λ) and meteorological parameters in near-ground atmospheric hazes are considered in this paper. To more adequately physically interpret the origin of variations, the total aerosol extinction coefficients are divided into components Δα1, Δα2 and Δα3 caused, respectively, by submicron (radius r≈0.05 to 0.45 μm), intermediately dispersed (r≈0.5 to 1.5 μm) and coarse (r>1.5 μm) particles. The relation of these characteristics with meterological parameters of the atmosphere are analyzed, and the role of different factors determining the variability of the aerosol extinction in visible and IR wavelength ranges is assessed.