Correlation between variations of aerosol extinction of visible and IR radiation in the near-ground layer and atmospheric column

Abstract

Statistical processing is performed for data sets obtained at the Tomsk site in 2003–2005 on the boundary-layer spectral extinction coefficient β(λ) and the bulk-atmospheric aerosol optical depth τ(λ) in the wavelength range λ = 0.44–4.0 μ m. It is found that the maximal correlation between variations in β(λ) and τ(λ) is observed in the 2003 set under conditions of increased smoke content. It is shown that this can be related to an increase in the variability range of the aerosol extinction of radiation along both boundary-layer and in the atmospheric column at the time of arrival of smoke formations at the observation site. The correlation coefficients ρ_βτ(λ) for the cleaner conditions of 2004 and 2005 are much lower. The calculated eigenvectors of the joint autocorrelation matrix {β _i (λ), τ _i (λ)} showed that the decrease in correlation between variations in β(λ) and τ(λ) can be related to the process of particle transport out of the ground level by convective and turbulent flows. This leads to aerosol depletion in the ground level and accumulation in the atmospheric column. The inverse process related to aerosol sedimentation is also possible.