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Published October 14, 2013 | Supplemental Material + Published
Journal Article Open

Los Angeles Basin airborne organic aerosol characterization during CalNex


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.

Additional Information

© 2013 American Geophysical Union. Received 12 March 2013; revised 13 September 2013; accepted 16 September 2013; published 14 October 2013. This work was supported by NOAA grant NA09OAR4310128. The authors would like to acknowledge the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) crew at the Naval Postgraduate School in Monterey, California for their support during CalNex. The authors would also like to acknowledge B. L. Lefer for use of the PBLH data from the CalNex Pasadena ground-site and W. T. Morgan for the use of their data in Figure 11. P.L.H. and J.L.J. thank CARB 08-319/11-305 and DOE (BER/ASR) DE-SC0006035/DE-FG02-11ER65293, as well as a CIRES Visiting Fellowship to P.L.H.

Attached Files

Published - jgrd50853.pdf

Supplemental Material - AMSvsDMAVol.pdf

Supplemental Material - LocationofIntercomparison.pdf

Supplemental Material - MSfpeakvary.pdf

Supplemental Material - OtoCvsLong.pdf

Supplemental Material - QContributions.pdf

Supplemental Material - ReadMeFileCravenCalNex.docx

Supplemental Material - SupplementalMaterialRRR.pdf

Supplemental Material - TSfpeakvary.pdf

Supplemental Material - ThreeFactorTs.pdf

Supplemental Material - VolumeTS.pdf


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August 22, 2023
October 26, 2023