The approach to the investigation of submicron atmospheric aerosol properties, developed over many years and conventionally called ‘the method of active spectral nephelometry’, is described in this paper. This approach is based on the principle of the separate study of the processes of variability of the dry matter of aerosol particles under the effect of external geophysical factors and their condensation activity supplemented by improved investigation of the physicochemical properties of particles by means of artificial influences and the technique for solving the inverse problem. Techniques for measurements and interpretation of data are presented, including solving the inverse problems of light scattering. The efficiency of the method for the study of the parameter of condensation activity and the growth factor of particles is shown based on the data of measurements in the real atmosphere. The results of thermo‐optical investigations of a submicron aerosol are presented. Seasonal and interannual behaviours of the optical parameters measured and microphysical characteristics of aerosol in the near‐ground layer of the atmosphere of west Siberia are analysed using the data from long‐term observations.

Measurement results of a complex of aerosol microphysical, chemical, and optical parameters in two cruises of the Akademik Mstislav Keldysh research vessel in 2016 are analyzed. The work was carried...

Considering the wide range of variability of all aerosol characteristics (especially in the near-ground layer of the atmosphere near industrial centers), when creating a realistic empirical model of optical and microphysical characteristics, the optimal dividing of the total data array according to some multifactor signs is needed. In this paper, we analyze the main states of “dry” aerosol on the basis of the results of long-term regular measurements in the near-ground layer of the atmosphere near the city of Tomsk in 2000–2017. The following parameters were considered: aerosol number concentration and size distribution function, total and angular scattering coefficients, including the small-angle range 1.2° to 20°, mass concentration and size distribution of absorbing substances (equivalent black carbon), characteristics of the aerosol hygroscopic properties, and spectral aerosol extinction of radiation on an open long path in the wavelength range 0.45 to 3.9 µm. In our comprehensive study, we first proposed and developed an original approach (classification) to study the optical and microphysical properties of atmospheric aerosol of various physicochemical origins (background, smoke, smog, anthropogenic, etc.) based on dividing the entire data array into characteristic subarrays (types of aerosol weather), which differ from each other in a different combination of scattering and absorbing properties of particles. To divide the total data array into types of aerosol weather including “Background”, “Haze-S”, “Smog”, and “Smoke haze”, the values of the scattering coefficient of the dry aerosol matter σ_d(λ = 0.51 μm) = 100 Mm⁻¹ and the ratio of the mass concentration of the absorbing substance to the mass concentration of submicron aerosol P = 0.05. The results showed that most of the seasonal average values of the aerosol parameters analyzed in the paper are statistically significantly different when comparing various characteristic types of scattering and absorbing atmospheric aerosol. The results of the research indicate that the application of the developed classification of types of aerosol weather for the analyzed optical and microphysical parameters of aerosol particles is quite effective and reasonable.

We present a new development stage of a generalized empirical model of optical characteristics of tropospheric aerosol in Western Siberia. An algorithm is suggested for taking into account the distribution function of absorbing matter and the condensation activity of aerosols as functions of aerosol particle sizes. Optical characteristics have been calculated with the complex refractive index of particles of different sizes variable with the relative air humidity. With aerosol weather types, referred to as “atmospheric haze” type (background and suburban haze), used as an example, the results of retrieving the angular scattering coefficients at small angles and the spectral behavior of the extinction coefficients are compared with experimental data.

The paper presents the generalized empirical model of the aerosol optical characteristics in the lower 5-km layer of the atmosphere of West Siberia. The model is based on the data of long-term airborne sensing of the vertical profiles of the angular scattering coefficient, aerosol disperse composition, as well as the content of absorbing particles. The model provides for retrieval of the aerosol optical characteristics in visible and near IR wavelength ranges (complex refractive index, scattering and absorption coefficients, optical depth, single scattering albedo, and asymmetry factor of the scattering phase function). The main attention in the presented version of the model is given to two aspects: The study of the effect of the size spectrum of the absorbing substance in the composition of aerosol particles on radiative-relevant parameters (the single scattering albedo (SSA) and the asymmetry factor (AF)) and the consideration of different algorithms for taking into account the relative humidity of air. The ranges of uncertainty of SSA and AF at variations in the modal radius of the absorbing fraction at different altitudes in the troposphere are estimated.

We consider the results of experimental study of the condensation activity of different-size particles; the study was performed from October 2020 to June 2021, using an AZ-10 photoelectric counter, equipped with a system for artificial humidification of atmospheric aerosol taken from the atmosphere. In parallel, hygrograms of the volume aerosol scattering coefficient were measured, using M903 integrating nephelometer. The atmospheric conditions and aerosol characteristics during the measurement period were typical, confirmed through a comparison with data from multiyear studies of the condensation activity parameter for the scattering coefficient at an angle of 45°.