A Multicomponent Magnetic Proxy for Solar Activity

Abstract

It has long been recognized that the Sun's radiative output is strongly correlated with the magnetic field (Gurman et al., 1974), which has been measured extensively over the past 50 years using both ground based and space based instruments. Furthermore, almost all of these measurements are spatially resolved, yielding information on the distribution of magnetic flux on the solar surface. Finally, the evolution of the surface magnetic field is well described by models, which provide a physics-based framework for forecasting solar activity. Surprisingly, there

Nowcasting Solar EUV Irradiance With Photospheric Magnetic Fields and the Mg II Index

“…Interestingly, the overall trend of the model-observation difference over the solar cycle does not change, with the models tending to predict more irradiance than observed during the decline of the solar cycle (2003)(2004)(2005)(2006)(2007) and less during the maximum (2002). Warren et al (2021) identify a similar trend in their models which they attribute to discrepancies in the weak magnetic fields (B r < 80 G) between the full-Sun magnetic maps and the original observed magnetograms. We identify two additional possible explanations for this effect.…”

“…Henney et al (2012); Henney et al (2015 used earth-side weak and strong solar photospheric magnetic field sums from global magnetic maps to estimate irradiance in EUV bands, along with F 10.7 . Similar work by Warren et al (2021) utilized more bins in the magnetic field strength combined with principle component analysis and demonstrated similar success modeling F 10.7 , Mg II, and selected EUV emission lines. This paper expands on the nowcasting components of Henney2012 and Henney2015 by focusing on Mg II rather than F 10.7 and using it to correct EUV nowcasts.…”

Overview of NASA's Solar Irradiance Science Team #2 (SIST-2) Program

“…The SUSIM solar UV spectrometers have complex sets of calibration options of multiple redundant optics and on-board deuterium lamps, and their recent analysis involves reanalysis of the in-flight calibrations in order to derive improved instrument degradation trending, which in turn can provide improved SSI variability results. Part of their research has also been the development of a solar magnetic proxy that can be useful for solar variability modeling (Warren et al, 2021). The project with the title "SORCE/TSIS Overlap Analysis: Absolute Scale Comparison, Stability Estimates, and Cycle 23/24//25 Record Construction" (project PI S. Beland) focuses on improving the SSI results from the Spectral Irradiance Monitor (SIM) aboard the SORCE satellite using the more accurate results from the TSIS-1 SIM instrument flying on the International Space Station (ISS).…”

Overview of NASA's Solar Irradiance Science Team #2 (SIST-2) Program

“…The SUSIM solar UV spectrometers have complex sets of calibration options of multiple redundant optics and on-board deuterium lamps, and their recent analysis involves reanalysis of the in-flight calibrations in order to derive improved instrument degradation trending, which in turn can provide improved SSI variability results. Part of their research has also been the development of a solar magnetic proxy that can be useful for solar variability modeling (Warren et al, 2021).…”