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Estimating error associated with a magnetic field model

Macmillan, Susan; Chulliat, Arnaud. 2015 Estimating error associated with a magnetic field model. [Poster] In: IUGG 26th General Assembly, Prague, Czech Republic, 22 June - 2 July 2015. (Unpublished)

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Abstract/Summary

A common requirement for users of magnetic field models is to have information about the accuracy of the model. Any signal not captured by the model is part of the error, for example the unmodelled crustal and external fields. Some models are used long after they have been produced and errors associated with prediction of the core field inevitably arise. Estimates of ground-based errors were derived as part of the recent World Magnetic Model production. These estimates were derived from vector data from observatories and repeat stations around the world combined with scalar data from marine and airborne surveys. The errors arising from the crustal and external fields have distinct spatial patterns, with local maxima in the auroral and polar regions for the external field. Declination, the element of the magnetic field of greatest interest to many users, is not linear in spherical harmonic model coefficients but can be propagated from the orthogonal components which are linear. This results in further spatial variations (inclination and horizontal and total intensities are also affected). Some of these propagation-related spatial variations are difficult to validate in ground-based measurements because of the poor spatial coverage. We investigate whether satellite data such as those from the Swarm mission can provide such validation. To derive all-inclusive error estimates for a particular magnetic field model, the errors from the crustal and external fields and core field prediction can be combined with the propagated error estimates.

Item Type: Publication - Conference Item (Poster)
NORA Subject Terms: Earth Sciences
Date made live: 05 Aug 2015 07:20 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/511437

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