Estimated Value of Magnetic Declination. - total magnetic intensity of the terrestrial field. To compute the magnetic declination, enter the location and date of interest. NOAA - National Geophysical Data Center.
Compute magnetic field values - (NOAA - National Geophysical Data Center) On-line calculators to estimate current and past values of the magnetic field.
Compute Historic Declination - (NOAA - National Geophysical Data Center)
National Geophysical Data Center - digital collection of geophysical data and observations of the solid earth, oceans and and Sun-Earth system, includeing Earth observations from space
Space Weather - news and Information about what's happening on the Sun and in space, such as sunspots, auroras and meteor showers, that could affect the Earth
USGS National Geomagnetism Program - information on observations and variations in the Earth's magnetic field
GRACE - Gravity Recovery and Climate Experiment - information on NASA Earth Observatory program to map Earth's gravity field