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JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 107, NO. B9, 2205, doi:10.1029/2001JB001389, 2002

Revised magnetic power spectrum of the oceanic crust

M. Korte

Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, USA


C. G. Constable

Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, USA


R. L. Parker

Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, USA


Abstract

The magnetic field originating within the Earth can be divided into core and crustal components, which can be characterized by the geomagnetic power spectrum. While the core spectrum is determined quite well by satellite studies, models of the shorter wavelength crustal spectrum disagree considerably. We reexamine aeromagnetic data used by O'Brien et al. [1999] to obtain a new, improved estimate of the crustal geomagnetic power spectrum. O'Brien et al.'s model somewhat failed to give a satisfactory connection between the longer-wavelength satellite studies and a reliable crustal model. We show that this was caused by an inadequate processing step that aimed to remove external variations from the data. We moreover attempt to bound the long-wavelength part of the spectrum using constraints of monotonicity in the correlation of the magnetization. However, this proves to be a weak constraint. Reversing the process, though, we are able to evaluate the correlation function using the reliable part of our geomagnetic spectrum. Thus we can obtain a sensible estimate for the long-wavelength part of the spectrum that is not well constrained by the data. Our new model shows better agreement with earlier satellite studies and can be considered reliable in the spherical harmonic degree range l = 30 to 1200.

Published 28 September 2002.

Index Terms: 1532 Geomagnetism and Paleomagnetism: Reference fields (regional, global); 1545 Geomagnetism and Paleomagnetism: Spatial variations (all harmonics and anomalies); 1599 Geomagnetism and Paleomagnetism: General or miscellaneous.

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Citation: Korte, M., C. G. Constable, and R. L. Parker (2002), Revised magnetic power spectrum of the oceanic crust, J. Geophys. Res., 107(B9), 2205, doi:10.1029/2001JB001389.