Thermodyamic Signature of Magnetic Cycles in Global Simulations of Solar Convection
Jean-François Cossette [cossette@astro.umontreal.ca], Université de Montréal, Groupe de
Recherche en Physique Solaire, Canada
Recent numerical simulations of global solar anelastic convection carried out with the
MHD version of the multi-scale model EULAG, broadly documented in the literature,
evidenced magnetic activity cycles with a spatially well-organized large-scale magnetic
component, antisymmetric about the equator and reversing polarity on decadal timescales. In
addition to the solar-like behavior of the large-scale magnetic field, the zonal mean potential
temperature perturbation about the ambient state profile varies in phase with the latter’s
amplitude and persists throughout the entire convection zone. This supports the thesis
according to which the observed decadal trend in Total solar irradiance (TSI) variations may
be the result of the combined effect of surface coverage by sunspots and active regions as
well as the thermodynamic signature of the internal dynamo mechanism, rather than the pure
contribution of the former. Ongoing work to quantify the contribution of such structural
changes to TSI variations using the EULAG seeks to incorporate a self-adjusting surface
deformation model and radiative transfer dynamics couplings to the present computational
framework.