Long-Term Observations of Aureole Scattering Phase Function in the Surface Air Layer in Suburbs of Tomsk (2010–2021)

The long-term data the aureole scattering phase function are analyzed for angles φ = 1.2° and 20° ( I 1.2 and I 20 ). They were measured with a closed-type halo photometer at the aerosol station in the V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, in 2010–2021. The interannual, annual, and daily variations in the parameters are analyzed. The daily averages of I 1.2 , I 20 are calculated from the hourly data, the monthly averages, from the daily averages, and the annual averages, from the monthly averages. A weak but significant (at the p = 0.05 level) time trend is found only for the interannual values of I 1.2 , 1.14% per year. In the annual behavior of I 1.2 ( I 20 ), we clearly discern a monotonic increase (decrease) from winter toward summer months. Smokes from distant wildfires in 2012 and 2016, and partly in 2018 and 2019, disturb this pattern with high I 20 values from July to September. The annual variations in the daily behavior of the monthly average I 1.2 , I 20 , and the ratio I 20 / I 1.2 are characteristic for continental surface aerosol. Smokes from distant wildfires lead to high I 20 values at nighttime, morning, and evening; and the decrease in I 20 in the daytime is not significant with the 0.95 probability due to large standard deviations.