Derivation, Meaning, and Use of Geomagnetic Indices
Copyright © 1980 by the American Geophysical Union.
Author(s): P. N. Mayaud
Published Online: 19 MAR 2013
Print ISBN: 9780875900223
Online ISBN: 9781118663837
Book Series: Geophysical Monograph Series
About this Book
Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 22.
Indices have evolved in fields where there are massive data ensembles to be digested and interrelated. Usually, an index will be formed from one specific variable that tends to characterize the whole. Thus we have indices such as the Gross National Product, the Consumer Price Index, sunspot numbers, and birth and death rates. Geomagnetic indices have enjoyed a long history that dates back to the days when observers would watch through a magnifying glass the oscillatory motions of the end of a long compass needle. Geomagnetic indices have been particularly successful because they can characterize the state of affairs of the entire magnetosphere as well as that of the surrounding interplanetary medium. Furthermore, of all the relevant parameters that might be used to form an index, geomagnetic variations have one of the longest histories, and they are supported by one of the oldest and best-established worldwide networks of observatories.