Statistics – Applications
Scientific paper
May 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agusm.p33a..03v&link_type=abstract
American Geophysical Union, Spring Meeting 2004, abstract #P33A-03
Statistics
Applications
1517 Magnetic Anomaly Modeling, 1545 Spatial Variations (All Harmonics And Anomalies), 1550 Spatial Variations Attributed To Seafloor Spreading (3005), 5440 Magnetic Fields And Magnetism, 6225 Mars
Scientific paper
The spectral method for distinguishing crustal from core-source magnetic fields has been re-examined, modified and applied to both a comprehensive geomagnetic field model and an altitude normalized magnetic map of Mars [Voorhies, Sabaka and Purucker, 2002; JGR]. These observational spectra are fairly fitted by theoretical forms expected from certain elementary classes of magnetic sources. For Earth we found fields from a core of radius 3512 +/- 64 km and a crust represented by a shell of random dipolar sources at radius 6367 +/- 14 km. For Mars we found only a field from a crust represented in same way, but 46 +/- 10 km below the planetary mean radius. More realistic theoretical spectra, allowing for crustal thickness, oblateness and magnetization by a planet centered dipole, were derived and discussed, as were spectral effects of laterally correlated sources. The main effect of laterally correlated sources is to soften the spectrum at high degrees. We tend to over-estimate source shell depth when this is omitted. To include this effect simply, size and magnetization distribution functions for extended sources are recast as a characteristic diameter and mean square magnetization amplitude for an ensemble of vertically magnetized spherical caps on a shell. For small caps, and at moderate degrees, the partial derivatives of the log-theoretical spectrum with respect to amplitude, shell radius, and cap diameter are approximately proportional to 1, n, and -n**2, respectively. Separation of diameter from amplitude and depth should thus be straightforward, unlike separation of amplitude from layer thickness. Results from applications to observational spectra are discussed, noting that there are now several fine field models for Mars [Cain et al., 2000; Connerney et al., 2001; Arkani-Hamed, 2001, 2002; Hutchinson and Zuber, 2002; Langlais et al., 2002]; moreover, the terrestrial magnetic spectrum at high degrees, as revised [Sabaka, Olsen and Langel, 2002], updated with high precision Oersted data, and upgraded with high resolution Champ data, appears softer than before.
No associations
LandOfFree
Crustal Magnetic Spectra from Correlated Sources on Mars does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Crustal Magnetic Spectra from Correlated Sources on Mars, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crustal Magnetic Spectra from Correlated Sources on Mars will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1177704