ectoterrestrial writes:
Interesting this should come up. There was a paper out yesterday about modeling the inverse solution to this region, as you well know. I've been unable to access a copy as of yet.

Alex writes:
The paper to which ecto is referring, which I've downloaded but not read in its entirety, was published online yesterday in JGR-Planets:

Parker, Robert L.
Ideal bodies for Mars magnetics
J. Geophys. Res. Vol. 108 No. E1
10.1029/2001JE001760
31 January 2003

Abstract

The high-amplitude magnetic anomalies observed by the Mars Global Surveyor imply the presence of a large intensity of magnetization in the Martian crust. We investigate the mathematical question of determining the distribution of magnetization that has the smallest possible intensity, without any assumptions about the direction of magnetization. The greatest lower bound on intensity found in this way depends on an assumed layer thickness. An analytical expression is discovered for the optimal magnetization, and numerical methods are described for solving the equations that determine the distribution. Some relatively small scale numerical calculations illustrate the theory. These calculations enable us to conclude, for example, that if the magnetization of Mars is confined to a 50-km thick layer, it must be magnetized with an intensity of at least 4.76 A/m.

Received 5 October 2001; revised 14 February 2002; accepted 25 April 2002; published 31 January 2003.

Keywords: Magnetization bounds, extremal models, nonuniqueness.

Index Terms: 5440 Planetology: Solid Surface Planets: Magnetic fields and magnetism; 6225 Planetology: Solar System Objects: Mars; 1545 Geomagnetism and Paleomagnetism: Spatial variations (all harmonics and anomalies); 3260 Mathematical Geophysics: Inverse theory.

Citation: Parker, R. L., Ideal bodies for Mars magnetics, J. Geophys. Res., 108(E1), 5006, doi:10.1029/2001JE001760, 2003.

ectoterrestrial writes:
I really have a hard time buying into the 'sea floor spreading' with reversing dynamo scenario. Maybe it's because I'm not looking at planetary science problems field from a Geoscience perspective but from a more abstract Physics position.

It's possible to get periodically varying phenomea from a number of simple processes which don't necessarily have an Earth analog.

Alex writes:
True, the reversing magnetic field *is* primarily a method of explaining the geoscientific observables (i.e., reversing polarity on both sides of a plate margin. However, in trying to understand the actual mechanisms at work, the geoscientists, as evidenced by Parker above, have entered the realm of abstract mathematics, that is chaos theory, to bridge the gap between Physics and Geoscience.

Alex R. Blackwell
University of Hawaii