Articles | Volume 10, issue 6
https://doi.org/10.5194/amt-10-2353-2017
https://doi.org/10.5194/amt-10-2353-2017
Research article
 | 
28 Jun 2017
Research article |  | 28 Jun 2017

Brown carbon absorption in the red and near-infrared spectral region

András Hoffer, Ádám Tóth, Mihály Pósfai, Chul Eddy Chung, and András Gelencsér

Abstract. Black carbon (BC) aerosols have often been assumed to be the only light-absorbing carbonaceous particles in the red and near-infrared spectral regions of solar radiation in the atmosphere. Here we report that tar balls (a specific type of organic aerosol particles from biomass burning) do absorb red and near-infrared radiation significantly. Tar balls were produced in a laboratory experiment, and their chemical and optical properties were measured. The absorption of these particles in the range between 470 and 950 nm was measured with an aethalometer, which is widely used to measure atmospheric aerosol absorption. We find that the absorption coefficient of tar balls at 880 nm is more than 10 % of that at 470 nm. The considerable absorption of red and infrared light by tar balls also follows from their relatively low absorption Ångström coefficient (and significant mass absorption coefficient) in the spectral range between 470 and 950 nm. Our results support the previous finding that tar balls may play an important role in global warming. Due to the non-negligible absorption of tar balls in the near-infrared region, the absorption measured in the field at near-infrared wavelengths cannot solely be due to soot particles.

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Short summary
Black carbon (BC) aerosols have been conventionally assumed to be the only light-absorbing carbonaceous particles that absorb visible light in the atmosphere. Here we report that, contrary to the conventional belief, tar balls (a specific type of organic aerosol particles from biomass burning) do absorb visible light more than previously thought. Our results support previous findings that tar balls play an important role in global warming.