Reducing the Backus effect given some knowledge of the dip-equator
Abstract
Geomagnetic field models computed from intensity measurements on or near the Earth's surface are plagued with strong errors known as the "Backus ef-fect". These errors are related to the mathematical non-uniqueness of the solution which can be theoretically removed by the knowledge of the dip-equator location. Here, we present. a new method for computing models using intensity data and additional information about the location of the dip-equator. We first give a numerical validation of this approach in an ideal case in which the dip-equator can be assumed to be perfectly located. We then show that in practice, updating a good past model of the field with a model of secular variation can constrain the location of the dip-equator sufficiently for our method to be useful. Implications for the planning of future satellite missions are briefly discussed.
Domains
Geophysics [physics.geo-ph]
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Ultr--Gu-rard_et_al-1998-Geophysical_Research_Letters.pdf (481.18 Ko)
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