Long-term observations of the aureole scattering phase function in the surface air layer of the suburbs of Tomsk (2010-2021)
Vas.V. Pol’kin, V.V. Pol’kin, M.V. Panchenko
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: small-angel scattering phase function, submicron and coarse atmospheric aerosol, temporal variability
Abstract
The long-term measurements of the aureole scattering phase function are analyzed for angles φ = 1.2° and 20° ( I1.2 and I20), which were obtained using a closed-type halo photometer at the aerosol station of the LAO of the IAO SB RAS in 2010-2021. The analysis of the temporal variability of the parameters was carried out for interannual and annual data and the diurnal behavior of hourly measurements. The daily averages were calculated from the hourly averages, the monthly averages, from daily averages and the annual averages, from the monthly averages. A weak but significant ( p = 0.05 level) time trend was found only for the interannual values of I1.2, which amounted to 1.14% per year. In the annual course of I1.2, a monotonous increase in the values from winter to summer months is clearly observed. In the annual course of I20, we see a decrease in values from winter to summer. Smokes from distant wildfires in 2012 and 2016 and partially in 2018 and 2019 disrupt this pattern with increased I20 values in July and insignificantly in June, August, and September. The diurnal behavior of the aureole scattering phase function values I1.2 and I20 and the ratios I20 / I1.2 constructed for the annual variation of monthly average daily values are typical of the behavior of surface aerosol under continental conditions. Smokes from remote wildfires lead to high values of I20 at night, morning, and evening, and the decrease in I20 during the daytime is insignificant with a probability of 0.95 due to the high standard deviation.
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