Authors: A I Shapiro W Schmutz M Dominique A V Shapiro
Publish Date: 2012/07/31
Volume: 286, Issue: 1, Pages: 271-287
Abstract
We analyze the light curves of the recent solar eclipses measured by the Herzberg channel 200 – 220 nm of the Large Yield RAdiometer LYRA onboard Project for OnBoard Autonomy PROBA2 The measurements allow us to accurately retrieve the centertolimb variations CLV of the solar brightness The formation height of the radiation depends on the observing angle so the examination of the CLV provide information about a broad range of heights in the solar atmosphere We employ the 1D NLTE radiative transfer COde for Solar Irradiance COSI to model the measured light curves and corresponding CLV dependencies The modeling is used to test and constrain the existing 1D models of the solar atmosphere eg the temperature structure of the photosphere and the treatment of the pseudocontinuum opacities in the Herzberg continuum range We show that COSI can accurately reproduce not only the irradiance from the entire solar disk but also the measured CLV Hence it can be used as a reliable tool for modeling the variability of the spectral solar irradianceThe research leading to this article was supported by the Swiss National Science Foundation under grant CRSI122130642 FUPSOL and grant 200020130102 We thank the PROBA2/LYRA science team for their work in producing the data sets used in this article and their helpful recommendations LYRA is a project of the Centre Spatial de Liège the PhysikalischMeteorologisches Observatorium Davos and the Royal Observatory of Belgium funded by the Belgian Federal Science Policy Office BELSPO and by the Swiss Bundesamt für Bildung und Wissenschaft PROBA2 is an ESA micro satellite operated by the Director for Science and Robotic Exploration
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