Relationship between Solar Magnetism and Irradiance

Aim of the team activities

The relationship between elements of the photospheric magnetic field and photospheric irradiance is the basis of most studies of solar irradiance variability, but in spite of much published work and many workshops on solar variations there is not yet a consensus on the experimental phenomenology. On the theoretical side considerable progress has been achieved, but there are still many open questions. The major open question is the relative contributions of surface magnetic variability and global changes to irradiance variations on various time scales. Since understanding the drivers of solar irradiance is a fundamental to interpreting the paleoclimate models which indicate climate change on the Earth, establishing the proper relation between solar magnetism and irradiance is one of the highest priorities in solar research.  The ISSI research team will produce a coherent description of the influence of the photospheric magnetic field on the solar irradiance, based on our best present knowledge.  The different data analysis methods historically applied to irradiance imaging and magnetograms (image processing, parameter calculations) will be compared and consensual empirical models produced. Recent numerical simulations of theoretical models on magnetic field structures and their effect on the newest irradiance measurements will be applied to the problem.  The experimental work will concentrate on solar cycle 23 data.

Team members

V. Domingo, University of Valencia, Spain  (team leader,
I. Ermolli, INAF Osservatorio Astronomico di Roma, Italy
P. Fox, High Altitude Observatory, Boulder, NCAR, Boulder, Colorado
C. Fröhlich, Davos Physikalisch-Meteorologisches Observatorium / WRC, Davos, Switzerland
G. Kopp, Univ. of Colorado / Laboratory for Atmospheric and Space Physics, Boulder, Colorado
M. Haberreiter, Davos Physikalisch-Meteorologisches Observatorium / WRC, Davos, Switzerland
J. Pap, Goddard Space Flight Center, Greenbelt, Maryland
J. Sánchez Almeida, Instituto de Astrofísica de Canarias, La Laguna,  Spain
P. Scherrer, Stanford University, California
W. Schmutz, Davos Physikalisch-Meteorologisches Observatorium / WRC, Davos, Switzerland
M. Schüssler, Max-Planck-Institut für Sonnensystemforschung, Lindau, Germany
S. Solanki, Max-Planck-Institut für Sonnensystemforschung, Lindau, Germany
H. Spruit, Max Plank Institut für Astrophysik, Garching, Germany
Y. Unruh, Imperial College, London, United Kingdom
W. Vögler, Max-Planck-Institut für Sonnensystemforschung, Lindau, Germany

Full Proposal text (open access)


First meeting: 11-15 October 2004 

First meeting attendees  Presentations (restricted access)

    V. Domingo                  facular contrast CLV in MDI images
    I. Ermolli                       PSTP, feature identification methods, modelling irradiacnce variations
    P. Fox                         
PSTP_2004, spectrum synthesis
    C. Fröhlich
    G. Kopp                       solar irradiance measurements
    M. Haberreiter              
modelling spectral UV variability
    J. Pap
    J. Sánchez Almeida
    P. Scherrer                    MDI calibration issue (by teleconference)
    W. Schmutz
    H. Spruit                        active regions enhanced cooling
    Y. Unruh
    W. Vögler

Minutes (restricted access)

meeting: 4-6 July 2005

Presentations (restricted access)

    V. Domingo                 la palma observations
    I. Ermolli                     PSTP images, intensity and magnetic measurements
    P. Fox                         radiative models
    C. Fröhlich                  MOD TSI composit revision             
    M. Haberreiter             COSI, model to calculate solar intensity spectra
     J. Pap                          
    S. Solanki                    simulations of magnetoconvection
    W. Schmutz
    H. Spruit                     

(restricted access)

Link to a draft of the webbook can be found here (
restricted access)

Third meeting:  6-9 June 2006