HR: 1340h
AN: GP33A-0928    [Abstracts]
TI: Application of Slepian Basis Functions to Magnetic Field Analysis of Saturn
AU: * Sterenborg, M G
EM: mgsteren@fas.harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, 20 Oxford street, Cambridge, MA 02138, United States
AU: Bloxham, J
EM: jeremy_bloxham@harvard.edu
AF: Department of Earth and Planetary Sciences, Harvard University, 20 Oxford street, Cambridge, MA 02138, United States
AB: Originally developed by communication engineers in an effort to maximize a signal's energy both in the time and spectral domain, these Slepian functions were later adapted by the geodetic community (Albertella 1999, Wieczorek 2005, FJ Simons 2003, 2006) to address the problem of incomplete datasets on the sphere. More often than not, Earth-observing satellites are not in a polar orbit, leaving the polar regions unsampled. Using traditional spherical harmonics for a spectral representation of such data can yield errors as they require global support to achieve orthogonality over the whole sphere. With the new basis functions, which are orthogonal over the whole sphere as well as over the region of data coverage, and which have their energy optimally concentrated in the spatial and spectral domain, we have carried out magnetic field analysis of Saturn. For Saturn, all datasets, from Pioneer 11, Voyager 1 and 2 and Cassini, primarily have their data concentrated on a latitudinal belt centered around Saturn's equator, leaving very large data gaps over the Kronian poles. Pioneer 11 and the Voyager probes were all flyby missions which took place more or less in the equatorial plane of Saturn and while Cassini will have a high inclination orbit later in its mission, thus far its data is limited to approximately 30 degrees around Saturn's equator. We have evaluated the advantages of the Slepian basis functions with respect to the more traditional spherical harmonic functions typically used in magnetic field analysis. In doing so, we have sought to characterize Saturn's magnetic field beyond that which is currently resolved, i.e. a spin-axisymmetric field with an uncertain rate of rotation.
DE: 1541 Satellite magnetics: main field, crustal field, external field
DE: 1595 Planetary magnetism: all frequencies and wavelengths
DE: 3260 Inverse theory
DE: 5734 Magnetic fields and magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Fall Meeting