Aerosol Layers in the Troposphere: Peculiarities of Variations in Aerosol Parameters at a Change in the Advection Direct
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MOTE SENSING OF ATMOSPHERE, HYDROSPHERE, AND UNDERLYING SURFACE
Aerosol Layers in the Troposphere: Peculiarities of Variations in Aerosol Parameters at a Change in the Advection Direction S. V. Samoilovaa, *, Yu. S. Balina, G. P. Kokhanenkoa, S. V. Nasonova, and I. E. Pennera aV.E.
Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, Tomsk, 634055 Russia *e-mail: [email protected] Received January 22, 2020
Abstract—Aerosol layers with different scattering and absorption properties are studied on the basis of the data of multifrequency sounding. The effect of air advection on the aerosol optical and microphysical parameters in the lower and middle troposphere is analyzed. It is revealed that the low values of the extinction and backscattering coefficients, as well as the imaginary part of the refractive index and mean geometric radius of fine particles are observed at the north transfer direction, and the high values of these parameters are at the south direction. On the contrary, the lidar ratio and the contribution of fine fraction into the total concentration of particles decrease when the direction has been changed from north to south. Keywords: aerosol, lidar, boundary layer, free troposphere, optical and microphysical parameters DOI: 10.1134/S1024856020040132
INTRODUCTION Atmospheric aerosol is one of the most variable components of the Earth’s atmosphere. The adequacy of climate and radiation models is largely determined by the reliability of data on the aerosol optical and microphysical properties. A variety of sources and sinks, the chemical composition of aerosol particles, and the high spatial-temporal variability of their properties require a comprehensive approach to obtain reasonable results of interpretation of the measurements. The main bulk of the aerosol in continental areas, is concentrated in the lower part of the troposphere, in the so-called boundary layer (BL), which consists of several sublayers [1, 2]: the lower (near-ground layer), middle (mixing layer), and upper (involvement layer). The most dynamic processes occur during daylight hours. The aerosol parameters of the upper BL sublayer, as well as the free troposphere, which is divided into the middle (MT, possible local layers) and upper (possible crystalline clouds) parts, are formed under the effect of the long-range horizontal transport. The ambiguity of their estimation in the middle BL sublayer is manifested in the impossibility of separating the contribution from local and remote sources. The analysis of the corresponding back trajectories of air mass according to the HYSPLIT data [3] helps to follow the history of formation of the aerosol composition at different altitudes. Studies of aerosol distribution over Western Siberia were carried out using various methods from onboard of the “Optik” aircraft-laboratory [4–8]. The diurnal, seasonal, and annual cycles in the BL sublayers are
analyzed, the main factors affecting the vertical variability of the aerosol content are considered, and paramet
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