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LITHOEN

Dataset

World Magnetic Model

Also known as WMM

A mathematical model of Earth’s main magnetic field, issued for a five-year epoch and revised as the field changes. It is a worked example of a model that is authoritative precisely because it is explicitly a model with a stated validity window.

How this record is known

1
Settled consensus
Cited as the accepted position of the discipline.
1
Interpretation
Reached by reasoning from evidence, or produced by a named model.

2 of 2 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.

What Lithoen records

Each claim states how it is known and cites its evidence.

EstablishedValid for a five-year epoch, then superseded.

The World Magnetic Model is revised every five years because Earth’s field changes: the current version was released in December 2024 and remains valid only until late 2029.

  • precision note: A validity window stated by the issuing agency, not an estimate.

Evidence support: Supported by the cited evidence one source

Evidence: NOAA National Centers for Environmental Information n.d. Primary authority

Model outputA spherical-harmonic representation with an explicit five-year validity epoch.

The World Magnetic Model represents Earth’s field with spherical-harmonic expansions and is issued for a five-year epoch, because secular variation means any such representation goes out of date.

  • model: World Magnetic Model (WMM), NOAA NCEI and the British Geological Survey.
  • method: Spherical-harmonic expansion fitted to observations and forecast forward across the epoch.

Evidence support: Supported by the cited evidence one source

Evidence: NOAA National Centers for Environmental Information n.d. Primary authority

In the knowledge graph

Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.