The large-scale solar variability through the cycle

Observational evidence for solar variability along the cycle has been considered. Two fundamental questions for the understanding of the solar structure and evolution are addressed :One concerning the detection of the large - scale dynamics of the convective zone which may be responsible for the generation and the maintenance of the solar differential rotation. There is evidence of a large - scale axisymmetric pattern (rolls) by observations of the meridional circulation and the transport of angular momentum by fluid motion. The rolls are time - dependent and are related to the torsional wave pattern.The second important question addresses the variability of the convective zone structure (radius and luminosity). Several independent observations favour a pulsation of the convective envelope, through cyclic variations of the radius and luminosity exhibiting the same periodicities as the magnetic sunspot cycle.It is suggested that we are in the presence of two strongly coupled cycles, a magnetic cycle and a convective pulsating cycle. The axisymmetric rolls (and related torsional oscillations) could be the main convective influence on the production of the magnetic field.