Show more...
Abstract:
Black carbon (BC) and light-absorbing iron oxides (FeOx) aerosols affect Earth's energy budget through their strong absorption of solar radiation. FeOx aerosols also can play a role as a nutrient for oceanic phytoplankton and thus potentially affects the global biogeochemical cycles. However, in-situ observation data of atmospheric concentrations and microphysical properties of these light-absorbing aerosols which are required for evaluating their climate effects using global models have been scarce, especially for FeOx aerosols. Here, we summarize and compare the datasets of BC and light-absorbing FeOx from five ground and three aircraft observation campaigns conducted in the East Asian and Arctic regions during the 2009-2018 period by using a modified single-particle soot photometer of the University of Tokyo. In all the campaigns, the majority (> 80%) of FeOx-containing aerosols in 170-270 nm FeOx size range has microphysical features of anthropogenic origin. The particle-size distribution for each of the BC and FeOx was similar among all the datasets, excepting the datasets dominated by fresh urban pollution or pristine arctic free-tropospheric air. The campaign-averaged mass concentration of FeOx (BC) in the East Asian and Arctic regions were ~100-400 (~300-1000) ng/m3 and ~5 (~25) ng/m3, respectively. Despite the large inter-campaign variation of their mass concentration, the campaign-averaged FeOx/BC mass concentration ratio were within a quite narrow range of 0.2-0.5 for all the campaigns. In each campaign, FeOx, BC, and carbon monoxide (CO) were tightly correlated with each other, implying the similarity of spatial distribution of their emission sources.