Studying solar irradiance variations using full-disk indices from continuum, UV, magnetic field and spectrographic data from ground and space-based images

This work addresses at least two components needed to support development of space-based TSI and SSI data sets as specified in Amendment No. 31 of program element A.49. The San Fernando Observatory?s (SFO) precision photometric processing on both SFO and Solar Dynamics Observatory (SDO) images creates irradiance proxies that 1) help determine relationships among different solar irradiance data sets and 2) allow the exploration of methods for bridging irradiance data gaps, both past and present, in the event of instrument or launch failure, as well as bridging different native scales from different spacecraft. Our team will prepare several data products in order to study their effects on both Total Solar Irradiance (TSI) and Spectral Solar Irradiance (SSI). First, the San Fernando Observatory continues to collect full-disk precision photometric data in multiple wavelengths, including red and blue continuum and Ca II K-line. As part of a database build, we will compare SFO sunspot and facular data to those of Debrecen (sunspot) and Bremen (Mg II K-line) (facular). Second, we will continue to add to the Solar Dynamics Observatory (SDO) solar indices, as determined with SFO algorithms, beyond where SIST2 ended. We are especially interested in the behavior of 1600Ã… and 1700Ã… wavelengths as solar activity ramps up in SC25. If possible, we would also like to add a magnetic flux index. Third, SFO is developing a new SSI data product for determining the photospheric and chromospheric line blending influence on SSI. SFO?s new f/5 echelle spectrograph with its f/1.8 cross-disperser grating produces spectra of the Sun-as-a-star in the visible and neighboring spectral range. Photospheric and chromospheric line strengths will be recorded daily, weather permitting. Combined with other previous observations, a long-range data product will be created to study the cyclic variation of different spectral lines in the Sun. We feel that comparing these data products and solar indices to TSI and SSI will contribute to a better understanding of the nature of solar variability.