Complex experiment on studying the microphysical, chemical, and optical properties of aerosol particles and estimating the contribution of atmospheric aerosol-to-earth radiation budget

The primary objective of this complex aerosol experiment was the measurement of microphysical, chemical, and optical properties of aerosol particles in the surface air layer and free atmosphere. The measurement data were used to retrieve the whole set of aerosol optical parameters, necessary for radiation calculations. Three measurement cycles were performed within the experiment during 2013: in spring, when the aerosol generation is maximal; in summer (July), when atmospheric boundary layer altitude and, hence, mixing layer altitude are maximal; and in late summer/early autumn, during the period of nucleation of secondary particles. Thus, independently obtained data on the optical, meteorological, and microphysical parameters of the atmosphere allow intercalibration and inter-complement of the data and thereby provide for qualitatively new information which explains the physical nature of the processes that form the vertical structure of the aerosol field

Химический состав аэрозоля в приземном слое прибрежной зоны Восточной Антарктиды

Chemical composition of aerosol in the ground layer of the coastal zone in East Antarctica is analyzed in the article. The aerosol samples were taken in 2006–2015 during seasonal works of the Russian Antarctic Expeditions (RAE), namely, these were 52nd–53rd, 55th, and 58th–60th expeditions. Samples were taken in the 200‑km band of the sea-shore zone along routes of the research vessels (REV) «Akademik Fedorov» and «Akademik Treshnikov» as well as on territories of the Russian stations Molodezhnaya and Mirny. Although the results obtained did show the wide range of the aerosol concentrations and a certain variability of their chemical composition, some common features of the variability were revealed. Thus, during the period from 2006 to 2014 a decrease of average values of the sums were noted. Spatially, a tendency of decreasing of the ion concentrations was found in the direction from the station Novolazarevskaya to the Molodezhnaya one, but the concentrations increased from the Molodezhnaya to the station Mirny. The sum of ions of the aerosol in the above mentioned coastal zone was, on the average, equal to 2.44 μg/m3, and it was larger than that on the territory of the Antarctic stations Molodezhnaya (0,29 μg/m3) and Mirny (0,50 ág / m3). The main part to the sum of the aerosol ions on the Antarctic stations was contributed by Na+, Ca2+, Cl−, SO4 2−. The main ions in aerosol composition in the coastal zone are ions Na+ and Cl−. The dominant contribution of the sea salt and SO4 2− can be traced in not only the composition of atmospheric aerosols, but also in the chemical composition of the fresh snow in the coastal areas of East Antarctica: at the Indian station Maitri, on the Larsemann Hills, and in a boring located in 55.3 km from the station Progress (K = 1.4÷6.1). It was noted that values of the coefficient of enrichment K of these ions decreases as someone moves from a shore to inland. Estimation of contributions of the continental and maritime factors to formation of the aerosol chemical composition revealed higher enrichment ratios for K+, Ca2+, SO4 2− (K = 3.6÷13.0). This reflects not only influence of the natural sources, but the intensity of human activities on the Antarctic continent as well. The elemental composition of solid aerosols was also analyzed. The largest concentrations were determined for Zn, Al and Fe. The ratio of concentration of the elements in both the soluble and insoluble phases of the aerosol showed that 84.1% of the total amount of the elements was contained in a water-insoluble state. Fractional relation between the element concentrations changed in different phases from 16 to 98%. High enrichment of the aerosol particles by Zn, Cu, Cr, Ba, Pb, Ni,Se, As, Cd (the enrichment factors = 27÷26 445) had been revealed. The content of dominant chemical components (Na+, Cl−, Zn, Fe), factors and coefficients of the element enrichment in the aerosols as well as in fresh snow of the coastal zone of East Antarctica are indicative of the identity of sources where their composition is formed.Рассмотрена временнáя и пространственная изменчивость химического состава атмосферного аэрозоля, отобранного в период сезонных работ 52, 53, 55, 58–60‑й РАЭ по маршруту следования НЭС «Академик Федоров» и «Академик Трешников» от станции Новолазаревская до станции Мирный. Заметное снижение суммы ионов в аэрозоле в 2007–2008 гг. хорошо согласуется с исследованиями в районе Восточной Атлантики и связано с гидрологическими процессами в Атлантическом океане. Установлено высокое обогащение аэрозольных частиц Zn, Cu, Cr, Ba, Pb, Se, As, Ni, Cd. Содержание преобладающих химических компонентов (Na+, Cl−, Zn, Fe), факторы и коэффициенты обогащения элементов (ФО = 27÷26 445) и ионов (K = 3,6÷13,0) в аэрозоле в поверхностном и свежевыпавшем снеге (K = 1,4÷6,1) прибрежной части Восточной Антарктиды свидетельствуют об идентичности источников формирования их состава

Statistical Estimation of the Atmospheric Aerosol Absorption Coefficient Based on the Data of Optical Measurements

The problem of the choice of the aerosol optical constants and, in particular, imaginary part of the refractive index of particles in visible and infrared (IR) wavelength ranges is very important for calculation of the global albedo of the atmosphere in climatic models. The available models of the aerosol optical constants obtained for the prescribed chemical composition of particles (see, for example, Ivlev et al. 1973; Ivlev 1982; Volz 1972), often are far from real aerosol. It is shown in (Krekov et al. 1982) that model estimates of the optical characteristics of the atmosphere depending on the correctness of real and imaginary parts of the aerosol complex refractive index can differ by some hundreds percent. It is known that the aerosol extinction coefficient {alpha}({lambda}) obtained from measurements on a long horizontal path can be represented as {alpha}({lambda})={sigma}({lambda})+{beta}({lambda}), where {sigma} is the directed light scattering coefficient, and {beta} is the aerosol absorption coefficient. The coefficient {sigma}({lambda}) is measured by means of a nephelometer. Seemingly, if measure the values {alpha}({lambda}) and {sigma}({lambda}), it is easy to determine the value {beta}({lambda}). However, in practice it is almost impossible for a number of reasons. Firstly, the real values {alpha}({lambda}) and {sigma}({lambda}) are very close to each other, and the estimate of the parameter {beta}({lambda}) is concealed by the errors of measurements. Secondly, the aerosol optical characteristics on the long path and in the local volume of nephelometer can be different, that also leads to the errors in estimating {beta}({lambda}). Besides, there are serious difficulties in performing spectral measurements of {sigma}({lambda}) in infrared wavelength range. Taking into account these circumstances, in this paper we consider the statistical technique, which makes it possible to estimate the absorption coefficient of real aerosol on the basis of analysis of simultaneous measurements of the spectral aerosol extinction coefficients {alpha}({lambda}), the directed scattering coefficient of dry aerosol {sigma}{sub 0}(0.55) and the mass concentration of aerosol containing BC (black carbon) Ms

Chemical composition of aerosol in the atmospheric surface layer of the East Antarctica coastal zone

Chemical composition of aerosol in the ground layer of the coastal zone in East Antarctica is analyzed in the article. The aerosol samples were taken in 2006–2015 during seasonal works of the Russian Antarctic Expeditions (RAE), namely, these were 52nd–53rd, 55th, and 58th–60th expeditions. Samples were taken in the 200‑km band of the sea-shore zone along routes of the research vessels (REV) «Akademik Fedorov» and «Akademik Treshnikov» as well as on territories of the Russian stations Molodezhnaya and Mirny. Although the results obtained did show the wide range of the aerosol concentrations and a certain variability of their chemical composition, some common features of the variability were revealed. Thus, during the period from 2006 to 2014 a decrease of average values of the sums were noted. Spatially, a tendency of decreasing of the ion concentrations was found in the direction from the station Novolazarevskaya to the Molodezhnaya one, but the concentrations increased from the Molodezhnaya to the station Mirny. The sum of ions of the aerosol in the above mentioned coastal zone was, on the average, equal to 2.44 μg/m3, and it was larger than that on the territory of the Antarctic stations Molodezhnaya (0,29 μg/m3) and Mirny (0,50 ág / m3). The main part to the sum of the aerosol ions on the Antarctic stations was contributed by Na+, Ca2+, Cl−, SO4 2−. The main ions in aerosol composition in the coastal zone are ions Na+ and Cl−. The dominant contribution of the sea salt and SO4 2− can be traced in not only the composition of atmospheric aerosols, but also in the chemical composition of the fresh snow in the coastal areas of East Antarctica: at the Indian station Maitri, on the Larsemann Hills, and in a boring located in 55.3 km from the station Progress (K = 1.4÷6.1). It was noted that values of the coefficient of enrichment K of these ions decreases as someone moves from a shore to inland. Estimation of contributions of the continental and maritime factors to formation of the aerosol chemical composition revealed higher enrichment ratios for K+, Ca2+, SO4 2− (K = 3.6÷13.0). This reflects not only influence of the natural sources, but the intensity of human activities on the Antarctic continent as well. The elemental composition of solid aerosols was also analyzed. The largest concentrations were determined for Zn, Al and Fe. The ratio of concentration of the elements in both the soluble and insoluble phases of the aerosol showed that 84.1% of the total amount of the elements was contained in a water-insoluble state. Fractional relation between the element concentrations changed in different phases from 16 to 98%. High enrichment of the aerosol particles by Zn, Cu, Cr, Ba, Pb, Ni,Se, As, Cd (the enrichment factors = 27÷26 445) had been revealed. The content of dominant chemical components (Na+, Cl−, Zn, Fe), factors and coefficients of the element enrichment in the aerosols as well as in fresh snow of the coastal zone of East Antarctica are indicative of the identity of sources where their composition is formed