The optical-microphysical characteristics of smokes from forest combustible materials with different contributions of flaming and smoldering combustion of biomass with 48-h ageing under dark conditions have been studied in the Big Aerosol Chamber of the Institute of Atmospheric Optics (IAO). The dynamics of spectral dependences of aerosol extinction coefficients at wavelengths of 0.45-3.9 µm, scattering and absorption coefficients at 0.46-0.63 µm, aerosol extinction, scattering, and absorption Angstrom exponents, Black Carbon (BC) mass concentration and relative BC content, and single scattering albedo was analyzed. Characteristics of model smokes have been compared with data for smoke plumes from remote Siberian wildfires to assess the mean values of the parameter of mixture of flaming/smoldering modes closest to the actual pattern of absorption properties of remote wildfires. A system for imitation of solar UV irradiation have been deployed in the Big Aerosol Chamber (BAC), and test experiments on generation of secondary organic aerosol under UV irradiation of the near-surface air pumped into BAC have been conducted.
A series of experiments in smokes of forest needle litter and pine wood in mixed combustion modes has been conducted in the Big Aerosol Chamber (BAC) of the Institute of Atmospheric Optics SB RAS. In the course of long (1-3 days) ageing of smokes, the correlations between the aerosol extinction coefficients in the wavelength range of 0.4 – 3.9 μm and directed scattering coefficients in the wavelength range of 0.46-0.63 μm were studied. The extinction and absorption Angstrom exponents are determined at different relative contributions of the smoldering/flaming modes.
The data obtained in 2000–2019 by the method of active spectral nephelometry using artificial humidification and heating of an aerosol collected from the atmosphere are analyzed. Measuring the response of the aerosol scattering coefficient to changes in relative humidity in the range of 30 - 90% and temperatures from 25 to 250°C makes it possible to indirectly evaluate the content of soluble/volatile species in the composition of particles. A combined analysis of the hygro- and thermo-optical parameters allows us to reveal the effect of compounds evaporating at various temperatures on the hygroscopic properties of particles.
The paper presents the results of one of the stages of development of the empirical model of the optical characteristics of tropospheric aerosol of Western Siberia. The model is based on classification by the types of aerosol weather constructed using the data of long-term measurements at the Aerosol station of IAO SB RAS. Here we discuss different variants of taking into account the aerosol absorbing and hygroscopic properties. The main feature of this paper is considering the size-resolved complex refractive index of particles. The results of model calculation are compared with the average experimental data on the angular scattering coefficient in the small-angle range and the spectral behavior of the aerosol extinction coefficients. It is shown that the most adequate reconstruction of the optical characteristics is reached in the case when the size distribution of absorbing substance has been described by a lognormal function and the dependence of the condensation growth factor on the particle size has been characterized by a maximum at a certain radius.
The data obtained in 2000–2017 by the method of active spectral nephelometry using artificial heating of an aerosol collected from the atmosphere up to 250°C are analyzed. The variability of thermo-optical parameters that determine the fraction of the volume concentration of particles evaporating in the corresponding temperature range depending on the type of “aerosol weather” is analyzed. Four data arrays characterized by different aerosol state were selected for each season: “background”, “haze”, “smog”, and “smoke haze”. The arrays differ in the level of concentrations of aerosol and soot. The peculiarities of the aerosol thermo-optical parameters in each type of turbidity are considered.
This article investigates data arrays obtained by using a closed-type aureole photometer. The arrays contain information about the scattering phase function for various types of «aerosol weather» in the angle range φ = 1.2–20º for the period 2010-2019. The total data array divided into types including «Background», «Haze-S», «Smog» and «Smoke haze». Data is formed on the basis of hourly values of the measured value. Long-term measurements in the surface layer of the Tomsk suburb showed that in winter and spring absolute values of directional scattering coefficients prevail for weather types, which are marked as “smog” and “smoky haze”, while values for “smog” prevail in winter and spring and in summer and autumn for the "smoky haze."
The results of monitoring of an aerosol in a near ground layer of the atmosphere of the suburb of Tomsk in this paper are discussed. The data were obtained for the years 2010-2018 at the aerosol station (V.E. Zuev Institute of atmospheric optics, Russian academy of sciences, Siberian branch) for scattering angles φ=1.2°, φ=20° with closed volume aureole photometer. The annual variations data are presented as absolute monthly average values, calculated from the hourly values of the I(φ) parameter. The analysis of the parameters of the average monthly values of the annual course revealed a certain periodicity, which was significantly affected by the natural fires of 2012. The presence of two maximums for I (1.2°), which are observed in the summer months of June-July and December and two minimums in March and November, is established. For I (20°), the maximum values are also observed in the summer months and winter in January, and the minimum in May and October.
Variability of the aerosol condensation activity parameter and the type of a hygrogram in different types of the “aerosol weather” are analyzed on the basis of the data of long-term measurements of the aerosol scattering coefficient as function of relative humidity of air in the near-ground layer of the atmosphere in the suburb of the city of Tomsk. Four data arrays different in the aerosol state: “background”, “haze”, “smog” and “smoke haze” are formed for each season. The analyzed data arrays were formed on the basis of the parameter σd (the scattering coefficient of the aerosol dry matter at the wavelength of λ = 0.51 μm), and P (ratio of the mass concentration of the absorbing substance to the mass concentration of submicron particles). The peculiarities of aerosol condensation activity at each type of aerosol weather are considered. It is revealed that the differences in the absolute values of the parameter of condensation activity and the type of hygrogram are caused by different values of σd (the level of aerosol content in the near-ground air layer), but the content of absorbing substance affects less.
In this article, the results of monitoring of an aerosol in a near ground layer of the atmosphere of the suburb of Tomsk are discussed. The submitted data are obtained by means of a closed volume aureole photometer allowing to measure round the clock an aureole scattering phase function in range of angles 1.2 - 20 degrees on the wavelength of 650 nanometers. The analysis and estimation of the difference in the mean monthly diurnal values in 2010-2017 carried out.
Based on data of seven expeditions, we considered the specific features of the spatial distribution of aerosol physicalchemical characteristics over Arctic seas in Russia. It is shown that the average aerosol and black carbon concentrations and aerosol optical depth of the atmosphere decrease by a factor of 2-2.5 in the direction from west to east. A more detailed analysis in the sectors of the Barents and Kara Seas revealed a tendency toward a decrease in aerosol characteristics in the northeast direction. We noted that the average ion concentrations in aerosol composition are close in value over the Barents and Kara Seas. Continental and maritime sources make nearly identical contributions to ion composition of aerosol over these seas.
To study the diurnal behavior of hygro- and thermooptical parameters, the cycles of intensive measurements with artificial humidification and heating of the aerosol under study were carried out four to six times a day. The parameter of condensation activity γ characterizes variability of the aerosol scattering coefficient under the change of the relative humidity of air, and the thermooptical parameters are determined by the decrease of the volume concentration of particles in the respective temperature range. Diurnal behavior of the parameter of condensation activity is the most pronounced in spring. Its characteristic peculiarities are maximum in the daytime (~ 3 pm) and minimum in the evening (~10 pm). Diurnal behavior of the parameter determining the aerosol fraction evaporated in the temperature range 100 – 250°C also is well pronounced.
The results of atmospheric aerosol monitoring are discussed. We compare data of particle size distribution function, which are obtained by photoelectric counter, with inversion of data closed volume aureole photometer, that’s allow us to measure the aureole scattering phase function in the range of angles 1.2-20 degrees at a wavelength of 650 nm. Seasonal variations and inter-annual differences collected from 2010 to 2015 years are analyzed and evaluated.
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.
In this paper, the data of directional scattering coefficient of aureole photometer for the scattering angles φ = 1.2°, φ = 4°, φ = 12° φ = 20° (collected from 2010 to 2015 years) to the data of traffic jams (presented by "Yandex traffic jams") is compared.
Inter-annual and seasonal variability of diurnal variations of the aureole scattering phase functions is analyzed. The data obtained by means of the completely automated aureole photometer with a closed scattering volume. Regular round-the-clock hourly measurements of the aureole scattering phase function were carried out in 2010-2014 at the Aerosol monitoring station of LOA IAO SB RAS in the region of scattering angles φ = 1.2 – 20° at the wavelength of 650 nm.
Latitudinal dependences of aerosol microphysical characteristics are analyzed. The data were obtained in the Russian Antarctic Expedition (RAE) onboard the expedition vessels "Akademik Fedorov" and "Akademik Treshnikov" in 2006- 2014, as well as the research vessel "Akademik Sergey Vavilov" in 2004.
Situations with scavenging of submicrometer aerosol particles by precipitation are analyzed. Experiments were carries out in Arctic region (NABOS expedition) onboard research vessels “Akademik Fedorov” and “Professor Khlyustin” in August-September 2013.
The conditions of variability of the submicron fraction of near-surface atmospheric aerosol with radii 0,3 ÷ 0,6 microns in transitional winter-spring period in the experiments carried out on aerosol station LOA IAO SB RAS in 2009-2013 are considered. A relationship between variations of the concentration of particles and submicron aerosol condensation activity is investigated.
Measurements of the mass concentrations of the dry matter of submicrometer aerosol and black carbon, black carbon fraction, size distributions and the volume filling factors of submicrometer and coarse particles, aerosol scattering coefficients at the angles of 45° and 1.2°, as well as the parameter of aerosol condensation activity are carried out in February 2014 at the Aerosol monitoring station IAO SB RAS. The dynamics of optical and microphysical characteristics of near-ground aerosol is analyzed. Their correlations and peculiarities of differences in urban winter smog in comparison with the conditions of weakly turbid atmosphere are studied. It is shown that multiple (more than an order of magnitude) increase of the content of submicrometer aerosol and black carbon in the near-ground layer occurs under conditions of a dense winter smog, that is comparable with events of high smoke content in the atmosphere due to forest fires in summer.
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.
We discuss the aerosol optical depth (AOD) measurements with the sun photometers onboard “Akademik Fedorov” and “Professor Khlyustin” research vessels in Arctic and Far East seas along the Northern Sea Route. Coastal observations in Barentsburg, Tiksi, and Vladivostok are employed to analyze the ship-based measurements. It is shown that AOD in Arctic differs little, with the average AOD values being much less than in the background midlatitude regions. In the spatial distributions of AOD and water vapor in Far East seas, we can clearly see the latitudinal dependence: all characteristics in the Bering Sea are close to data in the Arctic zone, these characteristics increase by a factor of 1.5-2 near south coasts of Kamchatka, and the difference reaches a factor of 4-6 in the region of Vladivostok.
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.
Nephelometers and photoelectric counters are the most widely used instruments for measuring the characteristics of
aerosol particles. Due to peculiarities of the design of the used nephelometer, as well as limited to visible range spectral
interval, sensitivity of the method is restricted to submicrometer aerosol fraction. On the contrary, counters provide for
the data on the particles with diameters of 1 μm and more. Thus, combination of these two instruments makes it possible
to extend the range of obtaining the reliable data on the aerosol microstructure.
In this paper, the results are discussed of simultaneous measurements of the size spectrum by means of nephelometer and
photoelectric counter at artificial humidification of aerosol in the range of relative humidity from 20 to 90%.
This paper is devoted to the analysis of variability of thermo- and hygrooptical characteristics of atmospheric aerosol particles obtained at artificial moistening and heating of aerosol sample. The tendency of decreasing the parameter of condensation activity during spring has been revealed. The relation between hygro- and thermooptical parameters are considered. The estimates of condensation activity of different aerosol fractions have been performed.
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