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MAGSAT satellite magnetic anomaly map over South AmericaA scalar magnetic anomaly map was prepared for South America and adjacent marine areas directly from original MAGSAT orbits. Special problems associated with the separation of external field and crustal anomalies, and the reduction of data to a common altitude are addressed. External fields are manifested in a long-wavelength ring current effect, a medium-wavelength equatorial electrojet, and short-wavelength noise. The noise is reduced by selecting profiles from quiet periods (Kp or = 3), and the effect of the electrojet is minimized by drawing the data set from dawn profiles only. The ring current is corrected through the use of a standard equation, augmented by further digital band-pass filtering. Profiles thus filtered differ primarily in amplitude due solely to satellite altitude differences. These differences are normalized by an inversion of the profile data onto a grid of equivalent point dipoles, and recalculated at an altitude of 350 km. The low altitudes in the study area cause instability in the inversion, necessitating separate inversions of several sub-areas which are subsequently merged. Crustal anomalies reduced-to-the-pole exhibit marked correlations to known tectonic features.
Document ID
19850023274
Acquisition Source
Legacy CDMS
Document Type
Other
Authors
Ridgway, J. R.
(Purdue Univ. West Lafayette, IN, United States)
Date Acquired
August 12, 2013
Publication Date
January 1, 1985
Publication Information
Publication: Improving the Geol. Interpretation of Magnetic and Gravity Satellite Anomalies
Subject Category
Earth Resources And Remote Sensing
Accession Number
85N31587
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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