1Atmopheric Optics Group GOA-UVA, University of Valladolid, Prado de la Magdalena s/n, 47071, Valladolid, Spain
2Izaña Atmospheric Research Center (CIAI), Meteorological State Agency of Spain\newline (AEMET), Spain
Abstract. The aim of the present work is to carry out a detailed analysis of columnar microphysical properties obtained from Cimel sun-photometer measurements in the Southwest of Spain within the frame of the AERONET-RIMA network. AERONET inversion products are analysed, in particular the particle size distribution together with their associated microphysical parameters for both fine and coarse modes: concentration, effective radius and the fine mode volume fraction. This work complements previous works based on aerosol optical depth (AOD) and the Ångström exponent (AE) for a global characterization of atmospheric aerosol in this representative area of Spain and Europe.
The analysed dataset spans between February 2000 and October 2008. Time series and statistical analysis has been carried out for these parameters in order to assess their typical values and seasonality together with their relationships with the AOD and AE. Mean values of volume particle concentration are 0.06 ± 0.07 μm3 μm−2 for total, 0.019 ± 0.015 μm3 μm−2 for fine and 0.04 ± 0.06 μm3 μm−2 for coarse mode; and of effective radius are 0.040 ± 0.19 μm for total, 0.14 ± 0.02 μm for fine and 1.96 ± 0.41 μm for coarse mode.
The most relevant features are the clear bimodality of the volume particle size distribution, with a slight dominance of the coarse mode for the total climatology and under the prevailing atmospheric conditions of the site (coastal marine). There is a clear prevalence of the coarse mode in summer months, September and March in coincidence with the occurrence of desert dust intrusions and highest AOD values. During aerosol desert dust arrivals, the particle size distribution is practically mono-modal with strong prevalence of the coarse mode which also shows a shift of the modal radius to lower values.
The size particle predominance defines the characteristic of the site and it has been analysed under two different approaches: with respect to particle number, using the Ångström exponent and with respect to particle volume, where the fine mode volume fraction Vf/Vt is taken.