Optical properties and aging of light-absorbing secondary organic aerosol
Item
Title (Dublin Core)
Optical properties and aging of light-absorbing secondary organic aerosol
Description (Dublin Core)
The light-absorbing organic aerosol (OA) commonly referred to as “brown carbon” (BrC) has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various volatile organic carbon (VOC) precursors, NO<sub><i>x</i></sub> concentrations, photolysis time, and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber-generated SOA samples, especially aromatic SOA, was found to increase with NO<sub><i>x</i></sub> concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficient (MAC) value is observed from toluene SOA products formed under high-NO<sub><i>x</i></sub> conditions at moderate RH, in which nitro-aromatics were previously identified as the major light-absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organic nitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible (Vis) and ultraviolet (UV) light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.
Creator (Dublin Core)
Liu, Jiumeng
Lin, Peng
Laskin, Alexander
Laskin, Julia
Kathmann, Shawn M.
Wise, Matthew
Caylor, Ryan
Imholt, Felisha
Selimovic, Vanessa
Shilling, John E.
Date (Dublin Core)
2018-09-19
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-16-12815-2016
https://acp.copernicus.org/articles/16/12815/2016/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
