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Geomagnetic Declination

HDGM provides higher resolution magnetic directional (or pointing) information than standard models. An example from Caspian sea.

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Real-Time Magnetic Disturbance

HDGM-RT is able to correct for disturbances caused by large geomagnetic storms.

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What's new in HDGM-2023

- Incorporated 9 years of data from the Swarm satellite mission
- Main field and secular variation update valid until December 31, 2023
- Updated main field model from 2021 to 2023
- Updated diurnal magnetic variations model in HDGM-RT

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What is HDGM

The High Definition Geomagnetic Model (HDGM) is a global, high resolution model of the Earth's geomagnetic main and crustal field, providing magnetic field values (total field, dip, and declination) at any point above or below the Earth's surface. Well planners can use HDGM to compute magnetic reference values at any point, as well as easily integrate HDGM into their directional drilling software. HDGM is updated annually to correctly model secular changes in the geomagnetic field. More Information

What is HDGM-RT

The Real Time add-on to the High Definition Geomagnetic Model (HDGM-RT) includes a model of Earth's external disturbance field which provides near real-time estimates of magnetic effects from current systems in the magnetosphere and ionosphere. It is based on near real-time ground observatory measurements of magnetospheric fields as well as solar wind observations from satellites. HDGM-RT includes all of the features available within the HDGM, plus access to the real-time magnetospheric and ionospheric field models. More Information


Compare Model FeaturesIGRFHDGMHDGM-RT
Average secular variation (5-year)
Rapid secular variation (1-year) 
150 km crustal resolution (satellite) 
25 km crustal resolution
(airborne/marine surveys)
Annually averaged disturbance field 
Real-time disturbance field (magnetosphere)  
Diurnal variation (ionosphere)