Los Angeles Basin airborne organic aerosol characterization during CalNex
Article first published online: 15 OCT 2013
©2013. American Geophysical Union. All Rights Reserved.
Journal of Geophysical Research: Atmospheres
Volume 118, Issue 19, pages 11,453–11,467, 16 October 2013
How to Cite
2013), Los Angeles Basin airborne organic aerosol characterization during CalNex, J. Geophys. Res. Atmos., 118, 11,453–11,467, doi:10.1002/jgrd.50853., , , , , , , , , and (
- Issue published online: 30 OCT 2013
- Article first published online: 15 OCT 2013
- Accepted manuscript online: 21 SEP 2013 04:05AM EST
- Manuscript Accepted: 16 SEP 2013
- Manuscript Revised: 13 SEP 2013
- Manuscript Received: 12 MAR 2013
- organic aerosol;
- Los Angeles
 We report airborne organic aerosol (OA) measurements over Los Angeles carried out in May 2010 as part of the CalNex field campaign. The principal platform for the airborne data reported here was the CIRPAS Twin Otter (TO); airborne data from NOAA WP-3D aircraft and Pasadena CalNex ground-site data acquired during simultaneous TO flybys are also presented. Aerodyne aerosol mass spectrometer measurements constitute the main source of data analyzed. The increase in organic aerosol oxidation from west to east in the basin was sensitive to OA mass loading, with a greater spatial trend in O:C associated with lower mass concentration. Three positive matrix factorization (PMF) components (hydrocarbon-like organic aerosol (HOA), semi-volatile oxidized organic aerosol (SVOOA), and low volatility oxidized organic aerosol (LVOOA)) were resolved for the one flight that exhibited the largest variability in estimated O:C ratio. Comparison of the PMF factors with two optical modes of refractory black carbon (rBC)-containing aerosol revealed that the coating of thinly coated rBC-containing aerosol, dominant in the downtown region, is likely composed of HOA, whereas more thickly coated rBC-containing aerosol, dominant in the Banning pass outflow, is composed of SVOOA and LVOOA. The correlation of water-soluble organic mass to oxidized organic aerosol (OOA) is higher in the outflows than in the basin due to the higher mass fraction of OOA/OA in the outflows. By comparison, the average OA concentration over Mexico City MILAGRO (Megacity Initiative: Local and Global Research Observations) campaign was ∼7 times higher than the airborne average during CalNex.