The results of two-point experiments on the estimation of the urban anthropogenic effect on the characteristics of atmospheric transparency

Abstract

To estimate the anthropogenic effect of the city of Tomsk on the measurements of the aerosol optical thickness (AOT) and the columnar water vapor of the atmosphere in the eastern suburb of Tomsk (Akademgorodok), two issues are discussed: (1) the comparative analysis of the data of simultaneous measurements in the suburban zone and at the background region (∼60-km distance), and (2) the dependence of the aerosol turbidity in the suburb on the air mass transfer direction. In addition to the spectral atmospheric AOT, we also considered two AOT components: fine and coarse aerosol. It is noted that variations of the atmospheric turbidity characteristics are mainly caused by synoptic-scale processes and manifest themselves similarly in urban and background regions. During the summertime, the AOT and columnar water vapor of the atmosphere in the two abovementioned regions are statistically indistinguishable, indicating the absence of the anthropogenic urban effect. During the cold period, the suburban zone may be characterized by higher atmospheric turbidity, seemingly due to the inversion accumulation of aerosol. The dependence of the AOT on the wind direction has the following features: (1) overall, the largest aerosol turbidity is observed during winds blowing from the southern sector; (2) during the cold period, the fine AOT component is, on average, 14% higher in cases of air mass transfer from the direction of the city (from the west and northwest directions); and (3) the coarse AOT component is slightly higher during westward air transfer than during an eastward one.