Resumen de la comunicación oral presentada en: 1st Iberian Meeting on Aerosol Science and Technology – RICTA 2013, celebrado del 1 al 3 de julio de 2013 en Évora, Portugal

Bennouna, Yasmine

Berjón, Alberto

Blarel, L.

Cachorro, Victoria E.

Canini, Marius

Dubovik, Oleg

Frutos, Ángel M. de

Fuertes, David

Goloub, Philippe

González, Ramiro

Molina, V.

Podvin, T.

Toledano, Carlos

Torres, Benjamín

English

Fuertes Marrón, David

Podvin, Thierry

Blarel, Luc

Frutos Baraja, Ángel Máximo de

Agencia Estatal de Meteorología

POINTING ERROR AND FIELD OF VIEW OF AERONET CIMEL-318 SUN PHOTOMETERS B. TORRES1-2, C. TOLEDANO1, A. BERJON3, D. FUERTES1, V. MOLINA1, R. GONZALEZ1, M. CANINI4, V.E. CACHORRO1, P. GOLOUB2, T. PODVIN2, L. BLAREL2, O. DUBOVIK2,  Y. BENNOUNA1, A.M DE FRUTOS1  1Group of Atmospheric Optics, Valladolid University, Valladolid, Spain, benjamin@goa.uva.es 2Laboratoire d´Optique Amosphérique, Université des Sciences et Technologies de Lille, Villeneuve d´Ascq, France. 3Izana Atmospheric Research Center, Spanish Meteorological Agency (AEMET), Tenerife, Spain. 4CIMEL Electronique, Paris, France  The pointing error has been shown to play an important role in the retrieval of aerosol properties from Sun/sky ground-based radiometers (Torres et al., 2013). This is especially critical in the case of coarse mineral particles (desert dust). Two new measurements, namely cross and matrix, have been added to the Cimel 318 radiometer, which is the standard instrument of the Aerosol Robotic Network (AERONET). These are both designed for the evaluation of the pointing error, although the matrix scenario also allows measuring the solid view angle of the instrument. First we have developed a method to derive the pointing error based on the cross and matrix data, including a correction for the Sun movement during the measurement, which must be taken into account for a correct evaluation of the pointing error. Both measurements reach similar results, with differences under 0.01º in the estimated pointing errors. Second, the pointing error of AERONET field instruments has been monitored by means of the cross measurement, that has been added to the standard measurement sequence of 10 photometers belonging to AERONET-Europe (calibrated at any of the AERONET calibration centers in Europe, i.e. LOA-Lille or GOA-Valladolid). The pointing errors are generally smaller than 0.1º although in some instruments values up to 0.3º have been observed. Moreover, the pointing error evaluation has shown that this measure can be used to detect mechanical problems in the robots or dirtiness in the quadrant detector due to the stable behavior of the values, for example with respect to time and solar zenith angle. Third, the matrix scenario can be used to derive the solid view angle of the radiometers. For that a method was implemented and five instruments were characterized. In order to provide a validation to the field of view measurement, a comparison with the field of view obtained with the vicarious calibration method was developed. The differences between both methods, which are completely independent, are under 3%.  

Pointing error and field of view of AERONET CIMEL-318 sun photometers

https://repositorio.aemet.es/bitstream/20.500.11765/7869/1/2_RICTA2013_FINAL38.pdf

Pointing error and field of view of AERONET CIMEL-318 sun photometers

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