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Please use this identifier to cite or link to this item: http://hdl.handle.net/10481/31808

Title: Technical Note: Determination of aerosol optical properties by a calibrated sky imager
Authors: Cazorla Cabrera, Alberto
Shields, J. E.
Karr, M. E.
Olmo Reyes, Francisco José
Burden, A.
Alados-Arboledas, Lucas
Issue Date: 2009
Abstract: The calibrated ground-based sky imager developed in the Marine Physical Laboratory, the Whole Sky Imager (WSI), has been tested with data from the Atmospheric Radiation Measurement Program (ARM) at the Southern Great Plain site (SGP) to determine optical properties of the atmospheric aerosol. Different neural network-based models calculate the aerosol optical depth (AOD) for three wavelengths using the radiance extracted from the principal plane of sky images from the WSI as input parameters. The models use data from a CIMEL CE318 photometer for training and validation and the wavelengths used correspond to the closest wavelengths in both instruments. The spectral dependency of the AOD, characterized by the A° ngstro¨m exponent in the interval 440–870 nm, is also derived using the standard AERONET procedure and also with a neural network-based model using the values obtained with a CIMEL CE318. The deviations between the WSI derived AOD and the AOD retrieved by AERONET are within the nominal uncertainty assigned to the AERONET AOD calculation (±0.01), in 80% of the cases. The explanation of data variance by the model is over 92% in all cases. In the case of , the deviation is within the uncertainty assigned to the AERONET (±0.1) in 50% of the cases for the standard method and 84% for the neural network-based model. The explanation of data variance by the model is 63% for the standard method and 77% for the neural network-based model.
Sponsorship: This work was supported by the Centro de Investigación Científica y Tecnológica (CICYT) of the Spanish Ministry of Science and Technology through projects CGL2007- 66477-C02-01 and CSD2007-00067 and the Andalusian Regional Government through project P06-RNM-01503 and P08-RNM-3568). First author has been funded by the Andalusian Regional Government and his research stay at University of California at San Diego has been also funded by the Andalusian Regional Government.
Publisher: Copernicus Publications
Keywords: UV erythema irradiance
Southeaster Spain
Atmospheric aerosols
URI: http://hdl.handle.net/10481/31808
ISSN: 1680-7316
Rights : Creative Commons Attribution-NonCommercial-NoDerivs 3.0 License
Citation: Cazorla, A.; et al. Technical Note: Determination of aerosol optical properties by a calibrated sky imager. Atmospheric Chemistry and Physics, 9: 6417-6427 (2009). [http://hdl.handle.net/10481/31808]
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