Volume 528, April 2011
|Number of page(s)||8|
|Published online||03 March 2011|
Monitoring the solar UV irradiance spectrum from the observation of a few passbands
1 LPC2E, UMR 6115, CNRS and University
of Orléans, 3A avenue de la Recherche
Scientifique, 45071 Orléans Cedex
2 LPG, UMR 5109, CNRS and University of Joseph Fourier, Bâtiment D de Physique, BP 53, 38041 Saint-Martin d’Hères Cedex 9, France
3 LATMOS, UMR 8190, CNRS, 11 boulevard D’Alembert, 78280 Guyancourt, France
4 Observatoire Royal de Belgique, Avenue Circulaire 3, 1800 Brussels, Belgium
5 Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Dr., Boulder, CO 80303, USA
Received: 10 October 2010
Accepted: 10 January 2011
Context. The solar irradiance in the UV is a key ingredient in space weather applications; however, because of the lack of continuous and long-term observations, various indices are still used today as surrogates for the solar spectral irradiance.
Aims. As an alternative to current spectrometers we use a few radiometers with properly chosen passbands and reconstruct the solar spectral irradiance from their outputs. The feasibility of such a reconstruction is justified by the high redundancy in the spectral variability.
Methods. Using a multivariate statistical approach, we first compared six years of daily-averaged UV spectra and a selection of passbands (from existing radiometers) and solar indices. This leads to a strategy for defining those passbands that are most appropriate for reconstructing the spectrum.
Results. With four passdbands chosen from already existing instruments, we reconstruct the UV spectrum with a relative error of about 20%. Better performance is achieved with a combination of passbands than with a combination of indices.
Key words: Sun: UV radiation / instrumentation: photometers / methods: statistical / methods: data analysis
© ESO, 2011
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