Title: Comparison Of CELIAS/SEM Spectral Irradiances With Other Solar Measurements And Indices

Authors: Floyd, L. E., D. R. McMullin and L. C. Herring

Reference: Proc. of the SOHO 11 Workshop, ed A. Wilson, ESA SP-508, 197. (2002)

Measurements from the Solar EUV Monitor (SEM), a component experiment of the Charge, Element, and Isotope System (CELIAS) aboard SOHO are analyzed in terms of coincident solar indices and simultaneous measurements made by other experiments. Earlier studies (e.g. Viereck et al., Floyd et al.) have shown the strong correspondence between the Mg II core-to-wing ratio and the SEM first order irradiance and by extension the inferred He II 30.4 nm emission line flux. These studies are extended by comparisons with the F10.7 (cm) radio flux, soft and hard x-ray fluxes as measured by the GOES satellites and the energetic solar proton flux also measured by GOES. We find that the solar protons are the cause of nearly all of the “spikes” in the first order flux and occur during proton flares. By contrast, solar protons do not have a significant effect on the measured central order flux, a channel sensitive to radiation in the 0.1–50 nm range. Solar x-rays explain a large portion of the central order flux, but do not affect the first order flux. The goal of these studies is to improve the time dependent models of EUV flux and will be extended to include the newly available SOHO EIT-derived irradiances.

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Last Update: 25 March 2003, Xuyu Wang