Long-Term Dynamics of the Large-Scale Magnetic Structures

Abstract

Large-scale magnetic field regions are evolving on a time scale of many weeks and months and are also modified during the solar activity cycle. The position of the regions are compared in a pair of consecutive synoptic charts and the horizontal velocity field responsible for their position changes, is inferred. Besides the axially symmetric zonal and meridional drifts, relating to differential rotation and meridional circulation, also non-axially symmetric velocity structures were observed during the last three solar activity cycles. Changes of the position and spatial distribution, as well as temporal variations of the field strength, closely relate to the occurrence and variations of other forms of solar activity such as sunspots, filaments and prominences and coronal structures. In combination with 11-yr cyclic changes of the large-scale velocity field, a new global dynamic regime of the convection zone is described.