English Geomagnetic secular variation Cited by user Artoria2e5 on 29 Jan 2022 Geomagnetic secular variation refers to changes in the Earth's magnetic field on time scales of about a year or more.
English Magnetic declination Cited by user Artoria2e5 on 29 Jan 2022 Magnetic declination, or magnetic variation, is the angle on the horizontal plane between magnetic north (the direction the north end of a magnetized compass needle…