Jordens magnetiska nordpol flyttar sig snabbt

The World Magnetic Model (WMM) is a large spatial-scale representation of the Earth's magnetic field. It consists of a degree and order 12 spherical harmonic expansion of the magnetic potential of the geomagnetic main field generated in the Earth’s core. Apart from the 168 spherical-harmonic "Gauss" coefficients, the model also has an equal number of spherical-harmonic Secular-Variation (SV) coefficients predicting the temporal evolution of the field over the upcoming five-year epoch. WMM is the standard geomagnetic model of the United States Department of Defense (DoD), the Ministry of Defence (United Kingdom), the North Atlantic Treaty Organization (NATO), and the World Hydrographic Office (WHO) navigation and attitude/heading reference. It is also used widely in civilian navigation systems. For example, WMM is pre-installed in Android and iOS devices to correct for the magnetic declination. The WMM is produced by the U.S. National Geophysical Data Center (NGDC) in collaboration with the British Geological Survey (BGS). The model, associated software, and documentation are distributed by the National Geophysical Data Center (NGDC) on behalf of National Geospatial-Intelligence Agency (NGA). Updated model coefficients are released at 5-year intervals, with the current model (WMM2015) expiring on December 31, 2019. The current World Magnetic Model (WMM2015) has been released on NGDC website on Dec 15, 2014. Because of extraordinarily large and erratic movements of the north magnetic pole, an out-of-cycle update to the WMM was released in January 2019 (delayed by a few weeks due to the US federal government shutdown).