HR: 0830h
AN: GP21A-0030    [PDF]
TI: A Global Crustal Magnetization Model of Mars Based on an $n=90$ Spherical Harmonic Model
AU: * Cain, J C
EM: cain@geomag.gfdi.fsu.edu
AF: GFDI and CSIT/Florida State University, GFDI, Tallahassee, FL 32306-4360 United States
AU: Purucker, M E
EM: purucker@geomag.gsfc.nasa.gov
AF: Raytheon ITSS at Geodynamics Branch, GSFC/Code 921, Greenbelt, MD 20771 United States
AU: Whaler, K A
EM: Kathy.whaler@ed.ac.uk
AF: Dept. of Geology and Geophysics/Univ. of Edinberg, West Mains Rd Scotland, Edinburgh, EH9 3J W United Kingdom
AB: Using a technique developed by KAW (originally in conjunction with the late Bob Langel) and MEP, a global crustal magnetization model for Mars was estimated using synthetic three--component vector data computed from an $n=90$ spherical harmonic model. These data were calculated on an approximately equal area grid at 100 km altitude. The areas are two degree squares of latitude and longitude at the equator expanding in longitude poleward similar to the data selection used in the $n=90$ model. This application for Mars has one less uncertainty than such work on Earth data because there is no need to separate a crustal field from an internal core field, but of course retains the basic ambiguity pointed out by Runcorn regarding the absolute level. A crustal thickness of 40 km was arbitrarily chosen as physically plausible though it has been shown that the thickness is not well resolved by satellite data. A spherical harmonic model computed from this model was also compared with one derived from the data that produced the $n=90$ model. In both instances the spectrum matches that published by {\it Cain et al.} (2003) for low degree, but is greatly diminished beyond $n=20$ as characteristic of a technique whose constraint is minimize the power in the model while satisfying the data. The calculation was implemented in OpenMP on an IBM Eclipse Regatta computing system utilizing 16 parallel processors on one node.
DE: 0903 Computational methods, potential fields
DE: 1517 Magnetic anomaly modeling
DE: 5440 Magnetic fields and magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting