The role of iron and black carbon in aerosol light absorption

[摘要] Iron is a major component of atmospheric aerosols, influencing the lightabsorption ability of mineral dust, and an important micronutrient thataffects oceanic biogeochemistry. The regional distribution of the ironconcentration in dust is important for climate studies; however, this isdifficult to obtain since it requires in-situ aerosol sampling or simulation ofcomplex natural processes. Simultaneous studies of aerosol chemicalcomposition and radiometric measurements of aerosol optical properties,which were performed in the Negev desert of Israel continuously for abouteight years, suggest a potential for deriving a relationship betweenchemical composition and light absorption properties, in particular thespectral single-scattering albedo.

The two main data sets of the present study were obtained by a sun/skyradiometer and a stacked filter unit sampler that collects particles incoarse and fine size fractions. Analysis of chemical and optical data showedthe presence of mixed dust and pollution aerosol in the study area, althoughtheir sources appear to be different. Spectral SSA showed an evidentresponse to increased concentrations of iron, black carbon equivalentmatter, and their mixing state. A relationship that relates the spectralSSA, the percentage of iron in total particulate mass, and the pollutioncomponents was derived. Results calculated, using this relationship, werecompared with measurements from dust episodes in several locations aroundthe globe. The comparison showed reasonable agreement between the calculatedand the observed iron concentrations, and supported the validity of thesuggested approach for the estimation of iron concentrations in mineraldust.

[学科分类] 大气科学