Download Abstracts Here - IGAC Project

List of Abstracts 224Observations 4.1 ID:4601 INVITED 08:30Atmospheric Organic Particulate Matter: Revisiting its Sources, Properties and ImpactsSpyros Pandis 1 , Neil Donahue 2 , Allen Robinson 21 University of Patras & Carnegie Mellon University2 Carnegie Mellon UniversityContact: spyros@andrew.cmu.eduAn overview of the development of our understanding of the sources, formation mechanisms, physical andchemical transformations of atmospheric organic aerosol (OA) is presented. Until recently, organicparticulate material was simply classified as either primary or secondary with the primary component beingtreated in models as nonvolatile and inert. However, this oversimplified view fails to explain the highlyoxygenated nature of ambient OA, the relatively small OA concentration gradients between urban areas andtheir surroundings, and the concentrations of OA during periods of high photochemical activity. A unifyingframework for the description of all components based on their volatility distribution (the volatility basis set)can be used for the treatment of a wide range of processes affecting organic aerosol loadings andcomposition in the atmosphere. These processes include direct organic particle and vapor emissions,chemical production of organic PM from volatile precursors, chemical reactions (aging) in all phases, as wellas deposition of both particles and vapors and chemical losses to volatile products. The combination of thisnew framework with the recent results of laboratory studies can resolve some of the discrepancies betweenOA observations and laboratory results.To illustrate the advances in the experimental techniques and theoretical tools in the study of atmosphericorganic aerosol we will combine ambient measurements from recent field campaigns in the US, Europe, andMexico City with chemical transport models. We focus on the ability of these models to reproduceobservations but also on their response to changes in emissions and climate.Observations 4.2 ID:4143 09:00Using ambient refractory particle mass to calibrate black carbon measurements made by laserinducedincandescence, thermal-optical transmittance, and filter-based photo-absorption techniquesYutaka Kondo, Lokesh Sahu, Nobuhiro Moteki, X. LiuUniversity of TokyoContact: y.kondo@atmos.rcast.u-tokyo.ac.jpThe total mass concentrations of fine-mode particles that were refractory at 400 °C (Mref) agreed with themass concentrations of black carbon (BC) measured by the thermal-optical transmittance method (Mtot) inTokyo, where the dominant sources of BC were emissions from diesel vehicles. The masses of the samerefractory particles were also used to calibrate BC mass measured by a single particle soot photometer (SP2),which uses laser-induced incandescence. This calibration agreed well with that of fullerene soot, whichindicates the consistency of the standards. Total BC mass concentrations measured with the filter-basedabsorption photometer continuous soot monitoring system referred to COSMOS (Mcosmos) operated at awavelength of 565 nm with a heated inlet were calibrated by Mtot at six different sites in Asia with avariability of about 7% in 2004–2007. Mcosmos values were also measured simultaneously with total BCmass concentrations measured with an SP2 (Msp2) in Tokyo for 9 days in 2009. Mcosmos and Msp2 werehighly correlated (r2 = 0.97) and agreed to within about 10% on average. These results demonstrate thatMsp2, Mcosmos, and Mtot are nearly identical to Mref. The use of mass concentrations of refractoryparticles for calibration of BC mass concentrations determined by means of different techniques gaveconsistent results, which allowed for the unambiguous definition of BC.iCACGP-IGAC 2010 15 July, 2010