Airborne in situ characterization of dry urban aerosol optical properties around complex topography
2006 (English)In: Atmospheric research, ISSN 0169-8095, Vol. 79, no 2, 148-174 p.Article in journal (Refereed) Published
In situ data from the 1997 Southern California Ozone Study—NARSTO2 were used to describe the aerosol optical properties in an urban area whose aerosol distribution is modified as the aerosols are advected over the surrounding topography. The data consist of measurements made with a nephelometer and absorption photometer onboard the Center for Interdisciplinary Remotely-Piloted Aircraft Studies (CIRPAS) Pelican aircraft. The cases investigated in this study include vertical profiles flown over coastal sites as well as sites located along some important mountain ranges in southern California.
The vertical distribution of the aerosol in the Los Angeles Basin showed a complex configuration, directly related with the local meteorological circulations and the surrounding topography. High spatial and temporal variability in air pollutant concentrations within a relatively small area was found, as indicated by the aerosol scattering and absorption coefficient data. The results suggest that in areas with such complex terrain, a high spatial resolution is required in order to adequately describe the aerosol optical quantities.
Principal components analysis (PCA) has been applied to aerosol chemical samples in order to identify the major aerosol types in the Los Angeles Basin. The technique yielded four components that accounted for 78% of the variance in the data set. These were indicative of marine aerosols, urban aerosols, trace elements and secondary aerosol components of traffic emissions and agricultural activities.
A Monte Carlo radiation transfer model has been employed to simulate the effects that different aerosol vertical profiles have on the attenuation of solar energy. The cases examined were selected using the results of the PCA and in situ data were used to describe the atmospheric optical properties in the model. These investigations comprise a number of sensitivity tests to evaluate the effects on the results of the location of the aerosol layers as well as the vertical resolution of the Monte Carlo model.
Place, publisher, year, edition, pages
Elsevier B.V. , 2006. Vol. 79, no 2, 148-174 p.
Urban aerosol; Airborne; Elevated layers; Optical properties; Topography; Montecarlo
Meteorology and Atmospheric Sciences
IdentifiersURN: urn:nbn:se:su:diva-24721DOI: 10.1016/j.atmosres.2005.05.005OAI: oai:DiVA.org:su-24721DiVA: diva2:198190
Part of urn:nbn:se:su:diva-7402005-11-212005-11-212010-12-08Bibliographically approved