Title: Vertical
extrapolation of Mars magnetic potentials
Author(s): Jurdy
DM, Stefanick M
Source: JOURNAL
OF GEOPHYSICAL RESEARCH-PLANETS 109 (E10): Art. No. E10005 OCT 15 2004
Document Type: Article
Language: English
Abstract: Mars
Global Surveyor (MGS) measured the most strongly magnetized crust in
the heavily cratered southern hemisphere of Mars. Our analysis
concentrates on the magnetic lineations or patterns centered near
latitude 40degreesS, longitude 180degreesW, with a range of values
+/-40degrees, using a rotated Cartesian coordinate system. We downward
continued the magnetic field measured at similar to400 km elevation and
very closely match the corresponding component measured during the
aerobraking phase at altitudes extending down to similar to100 km.
Using the vertical component of the magnetic field alone, we construct
a unique scalar potential and independently obtain from the derivatives
of this scalar potential the x and y components of the field. These
derived components agree very well with the observed horizontal
components. This demonstrates the validity and utility of the method
and the Cartesian approximation, and also it confirms the consistency
of the MGS magnetic data set. A model constructed with just 8 vertical
dipoles accounts for 80% of the variance of the scalar potential at 400
km over the region analyzed, but 14 dipoles can account for only 64% of
the variance at 100 km. We also construct the vector potential, the
curl of which generates the three components of the magnetic field.
This more complicated description may contain more physical meaning
than the scalar potential. The vector potential shows abrupt changes in
direction over the analyzed region, suggesting either different stages
of magnetization or local demagnetization.
Author Keywords: magnetic;
Mars; models
KeyWords Plus: FIELD
Addresses: Jurdy
DM (reprint author), Northwestern Univ, Dept Geol Sci, 1850 Campus Dr,
Evanston, IL 60208 USA
Northwestern Univ, Dept Geol Sci, Evanston, IL 60208 USA
Publisher: AMER
GEOPHYSICAL UNION, 2000 FLORIDA AVE NW, WASHINGTON, DC 20009 USA
IDS Number: 863RY
ISSN: 0148-0227