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- Detailed Aerosol Optical Depth Intercomparison between Brewer and Li-Cor 1800 Spectroradiometers and a Cimel Sun PhotometerPublication . Cachorro, Victoria; Berjón, Alberto Jesús; Toledano, Carlos; Mogo, Sandra; Prats, Natalia; de Frutos, Ángel M; Vilaplana, Jose Manuel; Sorribas, Mar; De La Morena, Benito Arturo; Gröbner, J.; Laulainen, Nels S.Aerosol optical depth (AOD) using different instruments during three short and intensive campaigns carried out from 1999 to 2001 at El Arenosillo in Huelva, Spain, are presented and compared. The specific aim of this study is to determine the level of agreement between three different instruments running in operational conditions. This activity, however, is part of a broader objective to recover an extended data series of AOD in the UV range obtained from a Brewer spectroradiometer. This instrument may be used to obtain AOD at the same five UV wavelengths used during normal operation for ozone content determination. As part of the validation of the Brewer AOD data, a Cimel sun photometer and another spectroradiometer, a Li-Cor 1800, were used. A detailed comparison of these three instruments is carried out by means of near-simultaneous measurements, with particular emphasis on examining diurnal AOD variability. Absolute AOD uncertainties range from 0.02 for the Cimel to 0.08 for the Brewer, with intermediate values for the Li-Cor 1800. All data during the comparison are in reasonable agreement, when taking into account the different performance characteristics of each instrument. The comparison also demonstrates current deficiencies in the Brewer data and thus the difficulty to determine AOD values with low errors.
- Columnar aerosol optical properties during “El Arenosillo 2004 summer campaign”Publication . Prats, Natalia; Cachorro, Victoria; Sorribas, M.; Mogo, Sandra; Berjón, Alberto Jesús; Toledano, Carlos; De Frutos, Ángel M; de la Rosa, Jesús D; Laulainen, Nels S.; de la Morena, Benito ArturoA detailed analysis of the columnar optical aerosol properties has been carried out for data collected during the ‘‘El Arenosillo 2004 summer campaign’’. These data are derived from a Cimel sun-photometer, as part of the PHOTONS-AERONET network at the El Arenosillo site in south-western Spain, over the period 1 June to 31 October 2004. Version 1 AERONET inversion products are used in the analysis. The aim of this campaign was to obtain a more complete set of data on aerosol particle microphysical, optical/radiative, absorbing and chemical properties for use in closure studies. In his paper we focus on the characterization of the aerosol optical depth (AOD)–alpha coefficients, and the particle size distribution together with their associated microphysical parameters, such as volume concentration, effective radius, etc., in order to define the features and ranges of these physical parameters associated with both fine and coarse particle modes. The requirement of high AOD values for using the inversion technique puts significant constraints on the estimation of the single scattering albedo (SSA) and refractive index, and thus requires great care in the analysis. As a result, only the characterizations of these parameters for desert dust events are considered reliable. Moreover, summer 2004 had the most frequent desert dust intrusions, including the most intense event (22–28 July and 31 July–2 August) ever recorded at the El Arenosillo site since the start of the measurements in February 2000. We summarize the results for the intensive summer campaign in terms of the range of values of the physical and optical parameters of the different aerosol types present in this area of Spain.