ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-27-3179-2009 Influence of the ozone profile above Madrid (Spain) on Brewer estimation of ozone air mass factor Antón M. 1 2 López M. 3 Costa M. J. 2 4 Serrano A. 1 Bortoli D. 2 Bañón M. 3 Vilaplana J. M. 5 Silva A. M. 2 4 Departamento de Física, Universidad de Extremadura, Badajoz, Spain Geophysics Centre of \'Evora (CGE), University of Évora, \'Evora, Portugal Agencia Estatal de Meteorología (AEMET), Madrid, Spain Department of Physics, University of \'Evora, \'Evora, Portugal Estación de Sondeos Atmosférico "El Arenosillo", Instituto Nacional de Técnica Aeroespacial (INTA), Huelva, Spain 14 08 2009 27 8 3179 3183 Copyright: © 2009 M. Antón et al. 2009 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/27/3179/2009/angeo-27-3179-2009.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/27/3179/2009/angeo-27-3179-2009.pdf

The methodology used by Brewer spectroradiometers to estimate the ozone column is based on differential absorption spectroscopy. This methodology employs the ozone air mass factor (AMF) to derive the total ozone column from the slant path ozone amount. For the calculating the ozone AMF, the Brewer algorithm assumes that the ozone layer is located at a fixed height of 22 km. However, for a real specific site the ozone presents a certain profile, which varies spatially and temporally depending on the latitude, altitude and dynamical conditions of the atmosphere above the site of measurements. In this sense, this work address the reliability of the mentioned assumption and analyses the influence of the ozone profiles measured above Madrid (Spain) in the ozone AMF calculations. The approximated ozone AMF used by the Brewer algorithm is compared with simulations obtained using the libRadtran radiative transfer model code. The results show an excellent agreement between the simulated and the approximated AMF values for solar zenith angle lower than 75°. In addition, the relative differences remain lower than 2% at 85°. These good results are mainly due to the fact that the altitude of the ozone layer assumed constant by the Brewer algorithm for all latitudes notably can be considered representative of the real profile of ozone above Madrid (average value of 21.7±1.8 km). The operational ozone AMF calculations for Brewer instruments are limited, in general, to SZA below 80°. Extending the usable SZA range is especially relevant for Brewer instruments located at high mid-latitudes.

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