Magnetic Field - Secular Variation of the Declination Component for the Epoch 2010.0 - Direct Download
Published By U.S. Geological Survey, Department of the Interior
Issued about 9 years ago
US
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Summary
Description
This map layer shows isoporic lines (lines of equal annual change, or secular variation, in the declination of the Earth's magnetic field), derived from the International Geomagnetic Reference Field (IGRF) for the epoch 2010.0. Magnetic declination is the angle between true north and magnetic north (the direction of the magnetic field vector) in the horizontal plane. The change is measured in arc minutes per year.