Abstract
Measurements at the AERONET station in Dushanbe showed that the diurnal variations of the aerosol optical thickness (AOT), humidity, Ångström parameter depend on the stratification of the atmosphere. It is established that the dynamics of the aerosol in the ground inversion temperature layer is determined by the effect of double diffusion, which is manifested as a result of the difference in the diffusion coefficients of the components. As the temperature and aerosol concentration increase from the bottom to the top, vertical convection cells of the "salt finger" type are formed, which cause a rapid settling of dust by means of condensation of water vapor and coagulation of particles and water droplets.
Highlights
The effect of rapid aerosol deposition was observed in Dushanbe more than 30 years ago, when during nephelometric measurements it turned out that for about two hours, in the morning and in the evening, the concentration of the surface aerosol increases dramatically
It was possible to carry out a detailed analysis after 2010 according to measurements of the solar photometer of the AERONET station
The diurnal variation of the dusty atmosphere parameters measured at AERONET station shows that the aerosol optical thickness (AOT), humidity and particle size are closely related to each other
Summary
The effect of rapid aerosol deposition was observed in Dushanbe more than 30 years ago, when during nephelometric measurements it turned out that for about two hours, in the morning and in the evening, the concentration of the surface aerosol increases dramatically. Later it turned out that during the rapid deposition of the aerosol there is a sharp decrease in the surface ozone content. The deposition of particles in these periods can even be seen when illuminated by a spotlight beam. It was possible to associate the observed phenomenon with the surface temperature inversion formed at the same time interval [1]. It turned out that during the surface inversion the aerosol optical thickness (AOT) and the humidity of the air sharply decrease and the particle size increases. After the end of the inversion, these parameters are restored almost to the previous level (Figs. 1, 2)
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