THE PECULIAR BEHAVIOR OF THE LARGE-SCALE COMPONENTS OF THE SOLAR MAGNETIC FIELD AS A RESULT OF ROSSBY VORTEX EXCITATION BENEATH THE CONVECTION ZONE

摘要

To interpret the dynamical features of large-scale magnetic fields, Rossby vortices are considered. Rossby vortices are assumed to be excited and sustained within a thin layer beneath the convection zone as a result of heating from the solar interior and deformation of the covection zone lower boundary. Numerical calculations show that a Rossby cyclone generates a large-scale magnetic structure, whose horizontal size compares with the solar radius. The distribution of the vertical component of the magnetic field bears a resemblance in this case to the cloud distribution in the cyclones that are observed in the Earth's atmosphere. A magnetic field with the sign of trailing polarity flux of the local bipolar magnetic regions and a field with the sign of leading polarity are generated, respectively, at the center of the Rossby cyclone and at the periphery. The drift of the cyclone toward the Sun's pole, caused by the Rossby wave emission, leads to a corresponding drift of the large-scale magnetic structure. Longitudinally averaged magnetic field distribution also drifts poleward and has a form of " double surge." The leading polarity is the first to reach the pole. The rotation of the first Fourier components of magnetic field calculated for the low- and midlatitude belts resembles in this case the real picture during the threefold polar field reversal in solar activity cycle. Rossby cyclones are used also to simulate some other situations on the Sun when, according to observational data, there are weak drifts of the longitudinally averaged component and corotation of the first Fourier components of the low- and midlatitude belts.