AERONET-RIMA calibration facilityAccuracy assessment of sky radiances in Autilla del Pino (Palencia-Spain)
- Torres, B.
- Berjón, A.J.
- Toledano, C.
- Cachorro, V.E.
- Fuertes, D.
- González, R.
- Bennouna, Y.S.
- Rodrigo, R.
- Frutos, A.M. De
ISSN: 2171-8814
Year of publication: 2011
Issue Title: 37th Amasom I
Volume: 44
Issue: 4
Pages: 665-669
Type: Article
More publications in: Óptica pura y aplicada
Abstract
Since 2006, RIMA network has a calibration facility for the Cimel sun photometers (intercomparison site at Autilla del Pino, Palencia). The calibration process and network management are carried out by the Atmospheric Optics Group of Valladolid University (GOA-UVa). This fact allows our group to run a large number of data from different co-located Sun photometers (Cimel-318). The comparison of radiance measurements has a special interest due to its importance in the inversion procedures. Differences between most of the sun photometers were under 5%, for direct comparison between sun-photometers since 2006, which is Aeronet acceptance limit. However, some discrepancies over this limit were found in some channels, especially in the aureole range and at 90º of almucántar angle. Problems in the pointing system are thought to be the causes of the differences at aureole range. Two new measurements have been implemented to evaluate and to improve the accuracy of pointing system in sun photometers: matrix and cross measurements. Errors at 90º at almucántar angle have been associated with old collimators. Aeronet network is installing new collimators so as reduce the differences.