Airborne analysis of the Los Angeles aerosol
Author
Collins, D. R.
Jonsson, H.H.
Liao, H.
Flagan, R.C.
Seinfeld, J.H.
Noon, K.J.
Hering, S.V.
Date
2000Metadata
Show full item recordAbstract
As part of the Southern California ozone study (SCOS), a research aircraft was employed during August and
September of 1997 to characterize the physical and chemical properties of the aerosol present over the Los Angeles Basin.
Aerosol size distributions measured using a di!erential mobility analyzer and two optical particle counters were
combined with "lter-based composition measurements to derive a physicochemical description of the aerosol sampled.
The accuracy of this description was evaluated through comparison of derived and directly measured aerosol properties
including mass, absorption coe$cient, hemispherical backscattering coe$cient, and total scattering coe$cient at two
di!erent relative humidities. The sampled aerosol exhibited a complex vertical structure possessing multiple elevated
aerosol layers. The most pronounced of these layers were observed to form by injection of aerosol above the ground-level
mixed layer along the southern edge of the San Gabriel Mountains, which form the northern boundary of much of the
Los Angeles Basin. Over multiple inland areas, additional layers were observed at about 2500 m above sea level (asl),
while o! the coast of Santa Monica, thin but concentrated layers were detected about 500 m asl. In addition to the sharp
vertical gradients in aerosol concentration observed, horizontal gradients at multiple locations were found to be su$cient
to result in more than 50% variability within a 5!5 km computational grid cell commonly used in atmospheric models.
Vertically resolved aerosol measurements made over one location during several #ights, as well as over several locations
during a morning and afternoon #ight on the same day, were used to investigate the temporally and spatially resolved
impact the aerosol had on gas-phase photolysis rates. These calculations predict that for a 103 zenith angle the sampled
aerosol enhanced photolysis rates by up to about 5%, although a slight decrease was often observed near ground
level.
Description
Atmospheric Environment, 34, 4155-4173.
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.Collections
Related items
Showing items related by title, author, creator and subject.
-
Characterization of ambient aerosol from measurements of cloud condensation nuclei during the 2003 Atmospheric Radiation Measurement Aerosol Intensive Observational Period at the Southern Great Plains site in Oklahoma
Rissman, T. A.; VanReken, T. M.; Wang, J.; Gasparini, R.; Collins, D. R.; Jonsson, H.H.; Brechtel, F. J.; Flagan, R. C.; Seinfeld, J. H. (2006);Measurements were made by a new cloud condensation nuclei (CCN) instrument (CCNC3) during the Atmospheric Radiation Measurement (ARM) Program’s Aerosol Intensive Observational Period (IOP) in May 2003 in Lamont, Oklahoma. ... -
Aerosols, clouds, and precipitation in the North Atlantic trades observed during the Barbados aerosol cloud experiment – Part 1: Distributions and variability
Jung, Eunsil; Albrecht, Bruce A.; Feingold, Graham; Jonsson, Haflidi H.; Chuang, Patrick; Donaher, Shaunna L. (Copernicus Publications on behalf of the European Geosciences Union., 2016-07-15);Shallow marine cumulus clouds are by far the most frequently observed cloud type over the Earth's oceans; but they are poorly understood and have not been investigated as extensively as stratocumulus clouds. This study ... -
The Marine Stratus/Stratocumulus Experiment (MASE): Aerosol-cloud relationships in marine stratocumulus
Lu, Miao-Lu; Conant, WIlliam C.; Jonsson, Haflidi H.; Varutbangkul, Varuntida; Flagan, Richard C.; Seinfeld, John H. (2007);The Marine Stratus/Stratocumulus Experiment (MASE) field campaign was undertaken in July 2005 off the coast of Monterey, California to evaluate aerosol-cloud relationships in the climatically important regime of eastern ...