Premium
Theories of the geomagnetic and solar dynamos
Author(s) -
Gubbins David
Publication year - 1974
Publication title -
reviews of geophysics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.087
H-Index - 156
eISSN - 1944-9208
pISSN - 8755-1209
DOI - 10.1029/rg012i002p00137
Subject(s) - dynamo , dynamo theory , earth's magnetic field , physics , solar dynamo , convection , dynamical systems theory , classical mechanics , theoretical physics , current (fluid) , ionospheric dynamo region , simple (philosophy) , magnetohydrodynamics , magnetic field , limit (mathematics) , geophysics , statistical physics , mechanics , mathematics , mathematical analysis , geomagnetic storm , quantum mechanics , philosophy , epistemology , thermodynamics
A review of recent advances in dynamo theory is presented in relation to the problems of the generation of the earth's and the sun's magnetic fields. Some relevant modern observations and estimates of physical quantities are discussed, and the lack of knowledge about the dynamical state of the earth's core is emphasized. The dynamo problem is conveniently separated into the kinematic approach, the area in which most work has been done so far, and the dynamical problem, which is exciting more current interest. Most attention is given to the low‐conductivity limit because this allows many of the theories to be exhibited in their simplest form. Dynamical dynamo models, driven either by an applied body force or by thermal convection, are described. Emphasis throughout the paper is on simple examples, at least as far as Cowling's theorem permits.