IAU Focus Meeting FM9:
Solar Irradiance: Physics-Based Advances

August 22 – 23, 2018

Scientific Rationale:

Understanding and modeling of solar-irradiance variability is important not only for solar physics but also for solar-terrestrial and solar-stellar studies. The latest irradiance measurements call into question aspects of currently-available empirical and semi-empirical models of solar-irradiance variability. A new generation of significantly more realistic physics-based irradiance models can now be created to incorporate recent advances in modeling and observing the solar atmosphere. This next generation of irradiance models will include new advances in MHD, surface flux transport, and radiative transfer simulations as well as new state-of-the-art solar data. By relying on physics-based understandings rather than merely empirical relationships established for the Sun, these new models will also allow more direct and physical extrapolations to other stars, opening a new regime for solar-stellar connection studies, as well as improved long-term estimates of historical solar variability.



  • Overview of existing solar-irradiance datasets (models and observations)
  • Proxies of long-term solar magnetic activity 
  • State-of-the-art in solar-irradiance modeling 
  • Simulations of solar surface magnetic field distribution with surface flux transport models 
  • Structure of solar magnetic features: What can we learn from MHD simulations? 
  • Radiative transfer calculations for next generation of irradiance models 
  • Brightness contrasts of solar magnetic features from high-resolution solar imagery (SUNRISE, SDO, HINODE, etc.) 
  • Solar-irradiance variability on timescales less than a day: magnetic and non-magnetic components 
  • Can we use solar models to explain brightness variations of Sun-like stars? 
  • Climate research needs for solar-irradiance time series: temporal and spectral coverage, critical issues, and priorities



Abstract list for FM9
Poster list for FM9

Wednesday, 22. Aug.

Overview of Issues
room: N
10:30 - Schmidt, Hauke (Solar Irradiance for Climate Studies)
11:00 - Solanki, Sami (Magnetic Features as Drivers of Solar Brightness Variability)
11:30 - Reiners, Ansgar (Brightness Variations of Sun-Like Stars)

Available Solar-Irradiance Data Sets and Models
room: F1
15:30 - Ball, Will (Long-Term Model-Based Reconstructions of the Solar Irradiance)
15:50 - Dudok de Wit, Thierry (Solar Irradiance: from multiple observations to a single composite dataset)
16:10 - Martchenko, Serguei (Solar Cycle 24: Accurate, Long-Term Solar Spectral Irradiance Measurements from Aura OMI)
16:25 - Snow, Martin (The SORCE Solar Spectral Irradiance Record: Fifteen Years of SSI)
16:40 - Walter, Benjamin (The latest TSI measurement results from the Compact Lightweight Absolute Radiometer (CLARA) onboard the NorSat-1 micro satellite)


Thursday, 23. Aug.

Available Solar-Irradiance Data Sets and Models and Brightness Contrasts of Solar-Surface Magnetic Features  
room: F1
08:30 - Schmutz, Werner (Assessing an uncertainty of the Total Solar Irradiance composite)
08:45 - Kretzschmar, Matthieu (How to model the variations of the Ly-a spectral irradiance?)
09:00 - Wu, Chi-Ju (Solar Irradiance Reconstruction over the Last 9 Millennia with a Multi-isotope Composite)
09:15 - RUTTEN, Robert (Non-Equilibrium Spectrum Formation affecting Solar Irradiance)
09:45 - Cernetic, Miha (Fast spectral synthesis for a new generation of solar and stellar brightness variability models)

Brightness Contrasts of Solar-Surface Magnetic Features
room: F1
10:30 - Criscuoli, Serena (Using MHD simulations of the solar atmosphere to reproduce irradiance variations: challenges and recent progresses)
11:00 - Ryabchikova, Tatiana (Atomic and Molecular Data Collections for Fine Spectral Analysis and Flux Calculations)
11:30 - Ermolli, Ilaria (Atmosphere models from inversion of high-resolution spectropolarimetric observations for solar irradiance reconstructions)
11:45 - Gravet, Romaric (Observations of UV contrasts and their impacts on the solar irradiance models)

Structure and Evolution of Solar-Surface Magnetic Fields
room: F1
13:30 - Hotta, Hideyuki (Calculations of the solar convection zone with the reduced speed of sound technique)
13:50 - Isik, Emre (Large-scale transport of solar magnetic flux)
14:10 - Raju Kuttickat (Variations of the Chromospheric Ca K Intensity from Kodaikanal Archival Data)
14:25 - Dibyendu Nandi (Modeling of Century-Scale Solar Activity and a Prediction for Cycle 25)
14:40 - Tripathi, Bindesh (Origin and recovery from grand solar minima in a time delay dynamo model with magnetic noise as an additional poloidal source)

Extrapolating Solar Models to Sun-like Stars
room: F1
15:30 - Egeland, Ricky (The Solar-Stellar Dynamo-Irradiance Connection: What Stellar Lightcurves Tell Us About How the Dynamo Works)
16:00 - Karoff, Christoffer (The Influence of Metallicity on Stellar Differential Rotation and Magnetic Activity)
16:30 - Nemec, Nina-Elisabeth (Solar brightness variations as they would be observed by Kepler telescope)
16:45 - Maehara, Hiroyuki (Statistical properties of starspots on solar-type stars and their correlation with flare activity)


  • Robert Cameron - Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany
  • Paul Charbonneau - Université de Montréal, Quebec (QC), Canada
  • Ilaria Ermolli - Osservatorio Astronomico di Roma, Roma, Italy
  • Juan Fontenla - NorthWest Research Associates, Boulder, USA
  • Mark Giampapa - National Solar Observatory, USA
  • Jie Jiang - Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, China
  • Greg Kopp - Laboratory for Atmospheric and Space Physics, Boulder, USA (co-chair and co-editor of proceedings)
  • Matthieu Kretzschmar - Univ. of Orleans & CNRS, Orléans, France
  • Natalie Krivova - Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany
  • Werner Schmutz - Physikalisch-Meteorologishes Observatorium Davos, World Radiation Center, Switzerland
  • Alexander Shapiro - Max-Planck-Institut für Sonnensystemforschung, Göttingen, Germany (co-chair & co-editor of proceedings)
  • Yvonne Unruh - Blackett Laboratory Imperial College London, UK
  • Ilya Usoskin - University of Oulu, Oulu, Finland
  • Aline Vidotto - Trinity College Dublin, Ireland




Greg Kopp:

Alexander Shapiro:


Link to External Website:


XXX IAU General Assembly | ACV - Austria Center Vienna  | Bruno-Kreisky-Platz 1  | 1220 Vienna