Global Geomagnetic Model Errors as a Function of Altitude and Geomagnetic Activity Space Weather

The errors of global geomagnetic models, such as the International Geomagnetic Reference Field and the World Magnetic Model (WMM), are well‐characterized at the Earth's surface, but their error behavior as a function of altitude and geomagnetic activity has not been quantified. A lack of error characterization at operational altitudes and during space weather events, however, introduces unquantified risk for system designers and satellite operators. This study provides the first comprehensive, multi‐source error analysis for the WMM from the surface to 10,000 km. We combine models for crustal, ionospheric, and magnetospheric fields to systematically quantify WMM performance across all levels of geomagnetic activity (G0–G4). Our results define the operational envelope where the WMM meets its Military Specification (MilSpec) accuracy. We demonstrate that while the model is robust at high altitudes (up to1,900 to 10,000 km, depending on the component) during quiet conditions, its validity ceiling can drop by thousands of kilometers during moderate to severe storms. We present maximum altitude validity maps and error profiles that provide a quantitative framework for mission planning, and real‐time risk assessment. These model‐based findings are validated using in situ measurements from the CHAMP, Swarm and CryoSat‐2 satellites. This work provides a resource for engineers and operators to assess and mitigate risks associated with using standard geomagnetic models for high‐altitude applications during space weather events.