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Annales Geophysicae An open-access journal of the European Geosciences Union
Ann. Geophys., 28, 1795-1805, 2010
https://doi.org/10.5194/angeo-28-1795-2010
© Author(s) 2010. This work is distributed under
the Creative Commons Attribution 3.0 License.
 
30 Sep 2010
Interpolation of externally-caused magnetic fields over large sparse arrays using Spherical Elementary Current Systems
S. A. McLay1 and C. D. Beggan2 1School of GeoSciences, University of Edinburgh, West Mains Road, Edinburgh, EH9 3JW, UK
2British Geological Survey, Murchison House, West Mains Road, Edinburgh, EH9 3LA, UK
Abstract. A physically-based technique for interpolating external magnetic field disturbances across large spatial areas can be achieved with the Spherical Elementary Current System (SECS) method using data from ground-based magnetic observatories. The SECS method represents complex electrical current systems as a simple set of equivalent currents placed at a specific height in the ionosphere. The magnetic field recorded at observatories can be used to invert for the electrical currents, which can subsequently be employed to interpolate or extrapolate the magnetic field across a large area. We show that, in addition to the ionospheric currents, inverting for induced subsurface current systems can result in strong improvements to the estimate of the interpolated magnetic field. We investigate the application of the SECS method at mid- to high geomagnetic latitudes using a series of observatory networks to test the performance of the external field interpolation over large distances. We demonstrate that relatively few observatories are required to produce an estimate that is better than either assuming no external field change or interpolation using latitudinal weighting of data from two other observatories.

Citation: McLay, S. A. and Beggan, C. D.: Interpolation of externally-caused magnetic fields over large sparse arrays using Spherical Elementary Current Systems, Ann. Geophys., 28, 1795-1805, https://doi.org/10.5194/angeo-28-1795-2010, 2010.
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