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State of the geomagnetic field

Chulliat, Arnaud; Brown, William ORCID: https://orcid.org/0000-0001-9045-9787; Alken, Patrick; Macmillan, Susan ORCID: https://orcid.org/0000-0001-6213-2672; Nair, Manoj; Meyer, Brian. 2021 State of the geomagnetic field. NOAA-NCEI, 13pp. (Unpublished)

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Abstract/Summary

The performance of the World Magnetic Model 2020 (WMM2020) was assessed by comparing its predictions at 2022.0 with that of a more recent model inferred from data collected by the European Space Agency Swarm satellites until September 2021. For all magnetic field components, the WMM2020 global root-mean-square error increased by less than 1.5% over the past two years and remained well below the maximum error allowed by the U.S. Department of Defense WMM specification. In addition, the WMM2020 secular variation was found to still be a very good approximation of the actual secular variation observed at ground-based observatories and Swarm-based geomagnetic virtual observatories in 2021. This suggests that nonlinear changes in the Earth’s magnetic field remained small over the past two years. Since 2020, the north (respectively south) magnetic dip pole has moved at an average speed of 44 km/yr (respectively 9 km/yr) without any noticeable change in direction. These movements led to minor changes in the shape and location of the WMM blackout zones, where compass accuracy is degraded. The South Atlantic Anomaly, where the geomagnetic field intensity is smallest, continued to deepen (by about 50 nT at sea level) and to move westwards (its center moved by about 50 km at sea level).

Item Type: Publication - Report (Technical Report)
Funders/Sponsors: National Oceanic and Atmospheric Administration, National Geospatial-Intelligence Agency, CIRES, NATO, Defence Geographic Centre, British Geological Survey
Additional Information. Not used in RCUK Gateway to Research.: This item has been internally reviewed, but not externally peer-reviewed.
Additional Keywords: World Magnetic Model, Geomagnetism, Magnetic field
Date made live: 20 Dec 2021 10:52 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/531589

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