Critical changes made to ensure accurate navigation
NOAA officials announced today the World Magnetic Model (WMM), a representation of Earth’s large-scale magnetic field and an indispensable complement to GPS devices used by NATO, the United States and United Kingdom militaries, as well as civil applications ranging from mineral exploration to smartphone apps, has been updated.

The WMM is a large-scale representation of Earth’s magnetic field. The blue and red lines indicate the positive and negative difference between where a compass points the compass direction and geographic North. Green lines indicate zero degrees of declination. (Image credit: NOAA)