Source characterization from ambient measurements of aerosol optical properties

Abstract

A general method to identify air masses impacted by distinct primary aerosol sources from in situ observations of optical properties of atmospheric aerosols is developed theoretically and tested against measurements made during the second New England Air Quality Study (NEAQS 2004) on board the NOAA R/V Ronald H. Brown. Distinct events are identified based on the observation of a temporal coherence in the relationship between a measured intensive optical property (i.e., single scatter albedo) and the extensive property of total light absorption of the sub‐micron aerosol. We show that this relationship can be used to differentiate between and quantitatively determine properties of the background aerosol and recent inputs of primary aerosol. Additionally, we show that the fraction of aerosol extinction (or aerosol mass) from primary emissions can be estimated from the albedo‐absorption relationship. During the NEAQS 2004 study, the primary aerosol was usually found to be highly absorbing, and thus likely to be derived from anthropogenic combustion sources. Overall primary aerosol contributed a relatively small amount (ca. 11%) to the total sub‐micron aerosol burden sampled onboard R/V Ron Brown.