Premium
Geomagnetism of Earth's core
Author(s) -
Benton Edward R.
Publication year - 1983
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/rg021i003p00627
Subject(s) - dynamo , dynamo theory , earth's magnetic field , outer core , geophysics , physics , mercury's magnetic field , inner core , ionospheric dynamo region , magnetic dipole , dipole , magnetic field , magnetism , ring current , geology , l shell , geomagnetic storm , quantum mechanics
It is widely accepted that terrestrial magnetism, an ancient, ever‐present but highly variable phenomenon, owes its existence to “self‐excited hydromagnetic dynamo action” taking place continuously in Earth's molten outer core. Yet, if the truth be admitted, this fine phrase actually enshrines a dynamical process whose details remain woefully obscure. As a result, geomagnetic dynamo theory should and does remain an active branch of modern geophysics. Some broad main issues at the center of this field include (i) the identification and location within the core of the energy source for the geodynamo; (ii) the form of the resulting fluid motions that both sustain and change the magnetic field; (iii) the strength of the unseen toroidal field in the core and the mechanism responsible for equilibration at that finite amplitude; (iv) the cause of angular tilt of the best‐fitting dipole and slow westward drift of the non‐dipole magnetic field; and (v) the mechanism underlying rapid, sporadic reversals of magnetic polarity.