The change of solar shape in time and depth. Some consequences for space climate

Abstract

During the last five years, studies of the Sun and Sun–Earth relationships have dramatically changed our view on solar terrestrial physics. We will here focus on new views on the solar interior. The internal non-homogeneous mass distribution and non-uniform angular velocity (function of the radial distance to the center and of the latitude) yield a complex outer shape. Beyond a “spherical” Sun is a new approach of solar-physics taking into account the gravitational energy which triggers the various layers. Such energy has been skipped in many ways up to now in theoretical models describing the solar output variability. In spite of many works on solar variations, there is not yet a consensus on the global experimental phenomenology. For instance, it is not yet known if this gravitational energy may explain faint observed irradiance variations, and the way the asphericity-luminosity parameter W acts on our stratosphere. Such issues must be solved to understand how the solar output variability may influence the Earth’s environment (helioclimatology). We will emphasize the key role of the subsurface layers (the leptocline, recently put in evidence by helioseismology) for a better prediction of the solar cycles. Regarding the solar core dynamics, the subject is of high priority for new investigations. We will conclude by giving some imprints on space-dedicated missions: GOLF-NG/DynaMICS in a joint effort with SDO (Solar Dynamics Observatory).