Retrieving the relative contribution of aerosol types from single particle analysis and radiation measurements and calculations: a comparison of two independent approaches

MARIANA ACHAD; MARÍA LAURA LOPEZ; GUSTAVO GERARDO PALANCAR; BEATRIZ MARGARITA TOSELLI

JOURNAL OF AEROSOL SCIENCE

ELSEVIER SCI LTD

Lugar: Philadelphia; Año: 2013 vol. 64 p. 11 - 23

0021-8502

The main purpose of this work is to determine the relative contribution of differenttypes of aerosols at an urban site by using two independent approaches: individualparticle analysis and radiative transfer calculations and irradiance measurements. Toaccomplish that purpose, we used our UV-B irradiance (280-315 nm) dataset, theAERONET (AErosol RObotic NETwork) database, the SEM (Scanning ElectronMicroscopy, LEO 1450VP) analyses of the collected particles and the Santa BarbaraDISORT Atmospheric Radiative Transfer (SBDART) model. On one hand, thecollected particles were analyzed by SEM-EDX (Energy Dispersive X-Ray, Genesis2000) in order to determine their chemical composition. Then, by using a developedalgorithm they were classified as rural or urban, resulting in a (24±3)% of rural and(76±8)% of urban. On the other hand, aerosols were incorporated into the SBDARTmodel through two of its default profiles (urban or rural) and by using the AerosolOptical Depth (AOD) provided by AERONET. The aerosol effect on experimentalsurface UV-B irradiance was reproduced by a linear combination of the irradiances calculated by using these profiles. From this analysis we found that, in average, a mix ofaerosols of (30±3)% rural and (70±7)% urban explains the observed reduction in theexperimental irradiance. Considering the agreement between the results obtained byusing these two independent methodologies, the use of the irradiance as a surrogatevariable to retrieve aerosol types is discussed. The methodology presented here isapplicable to any site provided irradiance measurements and AOD are available.