1IPGP - Institut de Physique du Globe de Paris (IPGP, 1 rue Jussieu, 75238 Paris cedex 05 ; Université Paris Diderot, Bât. Lamarck A case postale 7011, 75205 Paris CEDEX 13 - France)
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.
https://hal-insu.archives-ouvertes.fr/insu-01405111
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Submitted on : Tuesday, November 29, 2016 - 3:11:36 PM Last modification on : Sunday, January 3, 2021 - 3:03:46 AM Long-term archiving on: : Monday, March 27, 2017 - 8:48:16 AM
P Ultré-Guérard, M Hamoudi, G Hulot. Reducing the Backus effect given some knowledge of the dip-equator. Geophysical Research Letters, American Geophysical Union, 1998, 25 (16), pp.3201-3204. ⟨10.1029/98GL02211⟩. ⟨insu-01405111⟩