| 研究実績の概要 |
Brown carbon (BrC) aerosol is one of the most understudied aerosol components for its sources and effects on climate change. In this study, the light absorption properties and sources of BrC aerosols were investigated combining filter- and sky radiometer measurement based on SKYNET observation network. Filter samples were collected at Fukue Island and light absorption properties analyzed in the laboratory. The main light absorption properties were also analyzed based on sky radiometer observations. The light-absorption coefficient of BrC obtained from fillter measurements had a temporal trend similar to that of the ambient concentration of black carbon, indicating that BrC and black carbon have common combustion sources. After eliminating the contributions of BC, the absorption Angstrom exponent of BrC alone obtained from filter observations had a positive Spearman correlation (rs = 0.77, p < 0.1) with that derived from sky radiometer observations but 33% higher values, indicating that the light-absorption properties of BrC were successfully captured using the two methods. Using the atmospheric transport model FLEXPART and fire hotspots obtained from the Visible Infrared Imaging Radiometer Suite product, a high-BrC event was identified, which is related to an air mass originating from regions with consistent fossil fuel combustion and sporadic open biomass burning in central East China. The results of the study may help to clarify the dynamics and climatic effects of BrC aerosols in East Asia.
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