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The missing dimension in Magsat and POGO anomaly studies
Author(s) -
Purucker Michael E.,
Sabaka Terence J.,
Langel Robert A.,
Olsen Nils
Publication year - 1997
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/97gl52978
Subject(s) - magnetic anomaly , geology , lithosphere , geophysics , anomaly (physics) , magnetosphere , satellite , ionosphere , geodesy , magnetic field , seismology , physics , tectonics , quantum mechanics , astronomy , condensed matter physics
The development of a comprehensive model of the near‐Earth magnetic field in terms of sources in the core, ionosphere, and magnetosphere has allowed the isolation of heretofore unknown north‐south trending anomalies of lithospheric origin. Previously, along‐track filtering of satellite magnetic field data had been necessary in order to remove unmodeled magnetospheric and ionospheric magnetic fields. These fields change between adjacent passes by tens of nanoTeslas and have wavelengths which overlap the crustal spectrum. An example from Australia illustrates the additional information that can be extracted from the Magsat data set when this ‘missing dimension‧ is included. A north‐south trending low covers most of eastern Australia, in agreement with the aeromagnetic map of Australia. This feature is seen in both the dawn and dusk subsets collected from Magsat. The center of this low is roughly coincident with the Eromanga Basin but extends for almost 2000 km in a N‐S direction. The low corresponds to a region of almost featureless magnetic field on the aeromagnetic map. It is also consistent with an elevated geotherm previously proposed from studies of xenoliths in southeastern Australia. Filtering the new map in a north‐south direction reproduces the previous best estimate of the Australian satellite anomaly field. We expect that this comprehensive model will provide a new window into the magnetic field of the earth's lithosphere. The model continues to be enhanced.