Geomagnetic Declination

Example of improvement in declination at two sites in the Caspian sea (red crosses) by using the high resolution HDGM.

What's new in HDGM-2015

- Main field and secular variation update valid until 2017, using over 1 year of Swarm data!
- Model now covers years 1900-present
- 2010-2014 models retroactively updated with new Swarm data

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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.


- Easy integration with your well planning software of choice
- High resolution crustal field to degree 720 providing accurate down-hole declination values
- Main field and secular variation models spanning years 1900-present
- External field model to estimate disturbance field
- Uncertainty estimates using ISCWSA error model
- GUI executable and Excel interface
- C-language library source code included for custom development needs