PhD dissertation of Benjamín Torres Rodríguez
On April 4 2012, Dr. Benjamin Torres successfully defended his PhD dissertation “Study on the Influence of Different Error sources on sky radiance Measurements and investment-derived aerosol products in the frame of AERONET” at the University of Valladolid, obtaining the highest score, Apt “CUM LAUDE”. This PhD was supervised by Dr. Alberto J. Berjón, Izana Atmospheric Research Center (AEMET), and Dr. Carlos Toledano, Atmospheric Optics Group (University of Valladolid). It also counts with the participation of Dr. Oleg Dubovik, Laboratoire d’Optique atmospherique (Université de Lille – CNRS), as international tutor. This thesis presents the peculiarity of being the first presented at the University of Valladolid with the International mention.
From left to right in the photo: Alberto J. Berjón, Benjamín Torres, Oleg Dubovik and Carlos Toledano.
The main goal of this PhD is to contribute to the investigation of the causes behind the discrepancies between almucantar and principal plane retrievals, specifically, to examine if they can be associated with the errors in the radiance measurements. From the all possible sources of error (e.g. temperature dependencies, direct sun errors, clock errors, surface reflectance…) it focuses on the analysis of sky radiance errors that may lead to such discrepancies: calibration, pointing and finite field of view. It is important to remark that all three constitute systematic errors that cannot be reduced by averaging or other statistical procedures. If possible they should be corrected, in a similar way as it was shown for the direct sun channel calibration with the KCICLO method. However, correcting the systematic uncertainties is not always possible and a quantitative evaluation of such errors is therefore necessary. These errors are analyzed in terms of their effect on the radiance as well as their qualitative and quantitative impact on the aerosol properties that are retrieved by means of the AERONET inversion algorithm. It focuses on the size distribution, complex refractive index and single scattering albedo.