HR: 11:50h
AN: U41C-07 INVITED     [PDF]
TI: Effects of Thermal Core-Mantle Coupling on the Geodynamo
AU: * Olson, P
EM: olson@jhu.edu
AF: Peter Olson, Earth & Planetary Sciences Johns Hopkins University 3400 North Charles St, Baltimore, MD 21218 United States
AU: Christensen, U
EM: christensen@linmpi.mpg.de
AF: Ulrich. R. Christensen, Max Plank Institute for Aeronomy, Katlenburg-Lindau, 37191 Germany
AB: The response of the geodynamo to thermal core-mantle coupling is investigated using numerical dynamo models with nonuniform boundary heat flow. Small variations in boundary heat flow slightly perturb the geocentric axial dipole magnetic field, whereas large variations tend to kill the dynamo. Intermediate levels of boundary heat flow heterogeneity produce a variety of observable effects, including long-term departures from the geocentric axial dipole, azimuthal differences in secular variation, longitudinal bias during polarity changes, and azimuthal heterogeneity at the inner core boundary. We focus on dynamo models with boundary heat flow heterogeneity derived from the pattern of lower-mantle seismic tomography. These models offer explanations for several of the observed characteristics of the geomagnetic and paleomagnetic fields, including intense magnetic flux patches at high latitudes, westward drift below the Atlantic and weak secular variation beneath the Pacific, and non-random pole paths during polarity reversals.
DE: 1015 Composition of the core
DE: 3924 High-pressure behavior
DE: 7207 Core and mantle
DE: 8115 Core processes (1507)
DE: 8124 Earth's interior--composition and state (old 8105)
SC: U
MN: 2003 Fall Meeting