Svetlana A. Terpugova

Active spectral nephelometry as a method for the study of submicron atmospheric aerosols

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.

Optical–microphysical properties of smoke haze from Siberian forest fires in summer 2012

A comprehensive experiment on the study of dynamics of optical and microphysical characteristics of submicron aerosols in the near-ground air layer was carried out in June–August of 2012 under conditions of extremely strong smoke haze originating from vast forest fires in Siberia. Variations of the spectral angular scattering coefficients and the degree of linear polarization in the visible wavelength range are studied, as well as the mass concentrations of dry fractions of aerosol and black carbon, relative content of black carbon (BC fraction), single scattering albedo, particle size distribution function, complex refractive index of the particulate matter, and parameter of condensation activity of aerosol. Peculiarities of differences between optical and microphysical characteristics of near-ground aerosol in smoke haze and under smokeless conditions are revealed. This study is important for validation of results of remote sensing of the composition of smoke haze and background atmosphere obtained from satellite data and sun photometric measurements at the Aerosol Robotic Network (AERONET).

Estimation of Aerosol Radiation Effects under Background and Smoke-haze Atmospheric Conditions over Siberia from Empirical Data

The results of numerical simulation of downward solar radiation fluxes for background and smoke-contaminated atmospheric conditions are discussed. Vertical profiles of aerosol characteristics are obtained from the empirical model based on the data of aircraft sounding of profiles of angular scattering coefficients and content of absorbing particles in the lower troposphere. The background model was created using the results of measurements obtained under cloudless and mostly cloudless atmospheric conditions in 1999–2011. Optical parameters of smoke aerosol are determined from the data of aircraft measurements in the period of long-term wildfires in Siberia in the summer 2012. It is demonstrated that deficiency in diurnal values of total solar radiation at the surface level caused by the formation of the optically dense smoke layer as compared to background conditions, is more than 13 MJ/m2.

Multiyear variations in aerosol condensation activity in Tomsk

We consider the results of 13 years (1998–2010) of studies of the aerosol condensation activity in Tomsk. The long-term behavior of the condensation activity parameter exhibits, in addition to the annual cycle and its second harmonic, a tendency toward slower, ∼6–7-year oscillations. The values were maximum in 1998–1999 and 2005–2007. The annual average values were minimum in 2003 and 2008, i.e., in years when intrusions of subtropical air masses from arid regions of Kazakhstan and Central Asia were the most frequent.

Relationships between the optical and microphysical parameters of near-ground aerosol condensation activity

The results of measurements of the dependences of the aerosol optical characteristics on the relative humidity of air in artificial condensation processes are analyzed. The dependences of the condensation growth factors on the dry particle size are calculated and their statistical analysis is performed. The regression relation between the measured optical parameters of condensation activity and the Hanel parameter for the aerosol volume concentration is obtained. The possibility of the estimation of the Hanel parameter from the values of the refractive index of dry and humidified particles is shown.

Reconstruction of the Scattering Coefficient in the Lower Troposphere Using Ground-Based Measurements

Abstract The model proposed provides for reconstruction of the aerosol scattering coefficient profile. In so doing, one needs as input data the scattering coefficient value of the dry aerosol substance at the near-ground level measured at the wavelength of 0.52 μm, relative air humidity, aerosol optical thickness, and mean temperature of air in the lower troposphere. The model allows for the correlation between the values of the scattering coefficient at different altitudes, as well as the dependence of the height of the mixing layer on the heating of the lower atmospheric layers. The errors in reconstructing the vertical profiles of the aerosol scattering coefficient are analyzed for different ways of taking into account the external factors and input parameters. It is shown that the use of such an approach provides a decrease in the rms error in reconstruction even at this stage by approximately 30% for winter and by 3 to 4 times for summer in comparison with the rms deviation of this parameter in the i...

Model Estimates of Dynamics of the Vertical Structure of Solar Absorption and Temperature Effects under Background Conditions and in Extremely Smoke-Laden Atmosphere According to Data of Aircraft Observations

We present the quantitative estimates of the vertical distribution of absorbed solar radiation and temperature effects in the background and extremely smoke-laden troposphere of Siberia, obtained using empirical data and numerical simulation. Vertical profiles of the aerosol characteristics are created based on an empirical model, relying on aircraft sensing of angular scattering coefficients and the content of absorbing particles at different altitudes. It is shown that, under the smoke-haze conditions, the radiation effect of aerosol particles with high black carbon content on the diurnal influx of solar radiation in the central part of the smoke layer exceeds 50%. The change in air temperature due to the absorption of solar radiation during the daylight hours is approximately 2.5–5.5 K when the optical depth of the smoke aerosol varies in the range 2 ≤ τsmoke(0.55 μm) ≤ 4.

Structure of aerosol fields of the atmospheric boundary layer according to aerosol and Doppler lidar data during passage of atmospheric fronts

The paper presents the results of complex observations of the atmospheric boundary layer dynamics performed at the Fonovaya Observatory of the Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, in September 2013, with the use of remote sensing facilities, i.e., aerosol and Doppler lidars. The structure of aerosol and wind fields in the period of occurrence of internal buoyancy waves and low-level jet streams in the boundary layer is considered.

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.

Indirect method for estimation of the errors in measurements of sky radiance by Sun–sky radiometers of CIMEL type: calibration by molecular scattering

The results of measurements of the aerosol optical thickness (AOT) of the atmosphere by CIMEL Sun–sky radiometers are analysed. In arid zones, days with values of AOT not greater than 0.02 are common. In these cases, the sky radiance in backward hemisphere in the visible wavelength range is practically fully determined by the molecular scattering, which is well studied up to date. This fact opens up possibilities to estimate the errors in measuring sky radiance comparing observed and calculated data, as well as to separate them into random and systematic.