geomagnetic variation
geomagnetic variation
[¦jē·ō·mag¦ned·ik ver·ē′ā·shən] (geophysics)
Temporal changes in the geomagnetic field, both long-term (secular) and short-term (transient).
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.