Possibility of a 26- or 27-Month Periodicity in the Equatorial Geomagnetic Field

Abstract

Stacey and Westcott1 have presented evidence of an oscillation of somewhat more than two years in the geomagnetic field at one high latitude and three equatorial stations. The importance of this observation lies in its possible connexion with a large amplitude oscillation, of about the same period, in the winds of the equatorial stratosphere2. E. R. Hope, of the Canadian Defence Research Board, early this year, directed our attention to some Soviet literature3,4 on the subject of long-period geomagnetic variations. In these investigations, analyses of geomagnetic data from a number of Soviet stations appear to yield an oscillation of somewhat greater than two years. This work has recently been described by Hope5. Our comments6 accompanying Hope's note point out that the method of analysis may have been responsible for the apparent oscillation. The method of analysis used by Stacey and Westcott, at least in part of their paper (12-monthly minus 24-monthly running means), is similar to that used by Kalinin and Mansurov. In view of the possible implication of oscillations of about the same period in the geomagnetic field and in the equatorial stratospheric winds, a re-examination of the data was felt worth while.