STATE OF THE GEOMAGNETIC FIELD

Summary
The performance of the World Magnetic Model 2020 (WMM2020) was assessed by comparingits 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)

Click to access WMM_Annual_Report_2021.pdf

https://www.ngdc.noaa.gov/geomag/WMM/