HALF-WIDTH OF A SOLAR DYNAMO WAVE IN PARKERS MIGRATORY DYNAMO

A kinematic alpha omega-dynamo model of magnetic field generation in a thin convection shell with nonuniform helicity for large dynamo numbe rs is considered in the framework of Parker's migratory dynamo. The as ymptotic solution obtained of equations governing the magnetic field h as the form of an anharmonic travelling dynamo wave. This wave propaga tes over most latitudes of the solar hemisphere from high latitudes to the equator, and the amplitude of the magnetic field first increases and then decreases with propagation. Over the subpolar latitudes. the dynamo wave reverses; there the dynamo wave propagates polewards and d ecays with latitude. The half-width of the maximum of the magnetic fie ld localisation and the phase velocity of the dynamo wave are calculat ed. Butterfly diagrams are plotted and analysed and these show that ev en a simple model may reveal some properties of the solar magnetic fie lds.