IAU Commission E1 WG Solar Irradiance
Over the last decades, the importance of understanding solar variability and its influence on Earth climate has increased. To help achieve such understanding, solar irradiance measurements have improved in accuracy, stability, and spectral coverage, and a number of solar irradiance variability models have been created to better understand the mechanisms driving solar irradiance variability. These models can provide extended and uninterrupted irradiance records beyond the temporal- and spectral-ranges of the measurements themselves. While most of the models yield a qualitatively similar picture of solar irradiance variability, there are significant systematic discrepancies between their results. One particular example is that proxy-based and semi-empirical models indicate different solar irradiance variability in the UV. Additionally, the mechanisms of solar irradiance variability on centennial timescales are poorly understood, yet such long-term variability knowledge is critical for climate studies. These limitations will be improved by models incorporating more physics-based constraints and variability-range limitations suggested by comparisons with Sun-like stars. This requires a close collaboration between solar irradiance observers and modelers as well as coordinated assistance from experts in MHD simulations, radiative transfer, and synoptic stellar observations.
In this context, the main goal of the IAU Commission E1’s Working Group on Solar Irradiance is to improve collaborations between solar- and stellar-variability modelers and observers, promote further progress in the field of solar variability, and, since the interest in solar irradiance variability extends well beyond the solar community, recommend which solar irradiance datasets external researchers use.