Accession Number : AD0678083

Title :   THERMALLY DRIVEN ROSSBY-MODE HYDROMAGNETIC DYNAMOS,

Corporate Author : COLORADO UNIV BOULDER

Personal Author(s) : Gilman,Peter A.

Report Date : SEP 1968

Pagination or Media Count : 67

Abstract : A new class of hydromagnetic dynamos is presented for which the fluid motions are large-scale Rossby waves in a zonal flow, driven by latitudinally non-uniform heating. The magnetic fields induced by these motions are allowed to react upon them, through electromagnetic body forces. The model actually solved is confined to a channel between latitude walls, has two layers in the vertical, and a small number of Fourier harmonics in the horizontal. It is a generalization of the non-magnetic model developed by Lorenz to study vascillation, and of earlier work by the writer. Most of the dynamos found have periodically reversing magnetic fields; the period depends principally on the strength of the inducing motions. Fields in successive cycles increase until they are strong enough to alter the motion and thereby reduce induction, after which induction of new fields is balanced by dissipation, on the average. Magnetic energy typically reaches 10% of the kinetic energy of the inducing motions. Some non-reversing dynamos are also found. The results, including field amplitudes, periods of reversal, and particularly the process of field reversal compare reasonably well with observed properties of the solar cycle. (Author)

Descriptors :   (*SUN, *MAGNETOHYDRODYNAMICS), MAGNETIC FIELDS, CONVECTION(HEAT TRANSFER), PERIODIC VARIATIONS, MATHEMATICAL MODELS

Subject Categories : Astrophysics
      Plasma Physics and Magnetohydrodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE