State of the Geomagnetic Field

National Centers for Environmental Information (U.S.), British Geological Survey. 2023 State of the Geomagnetic Field. National Centers for Environmental Information (U.S.), 21pp.

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Abstract/Summary

The performance of the World Magnetic Model 2020 (WMM2020) was assessed by comparing its predictions on January 1, 2024 with that of a more recent model inferred from data collected by the European Space Agency (ESA) Swarm satellites until September 2023. For all magnetic field components, the global root-mean-square error of WMM2020 increased by less than 10% of its previous value over the past four 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 again deemed an accurate approximation of the actual secular variation observed at ground-based observatories and Swarm-based geomagnetic virtual observatories up to 2023. This suggests that nonlinear changes in the Earth’s magnetic field have remained small over the past three years. Since 2020, the north magnetic dip pole has moved at an average speed of 41 km/yr, and the south magnetic dip pole at 9 km/yr. Neither underwent 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 highly degraded. The South Atlantic Anomaly, where the geomagnetic field intensity is lowest, has continued to deepen (by about 25 nT at surface level) and move westward (its center moved by about 20 km at surface level) in the past year. Over the past year, three strong to severe geomagnetic storms occurred, leading to significant (e.g., declination deviations over 9 degrees) but temporary effects on WMM performance, mostly at high geomagnetic latitudes. As WMM2025 is anticipated for release in December 2024, this marks the final report on WMM2020.

Item Type:	Publication - Report (Technical Report)
Digital Object Identifier (DOI):	10.25923/cww1-sc35
Funders/Sponsors:	Defence Geographic Centre, National Geospatial-Intelligence Agency, National Centers for Environmental Information (U.S.), NATO, British Geological Survey, National Oceanic and Atmospheric Administration
Additional Information. Not used in RCUK Gateway to Research.:	Released under CC0 1.0 DEED licence.
Additional Keywords:	Geomagnetism; World Magnetic Model
Date made live:	08 Jan 2024 17:30 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/536489

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