The geomagnetic field and Sq

Abstract

The process of conductivity modelling using results for internal and external components of daily magnetic variations and their seasonal changes gives consistently poor results from Sq at 1 c per day and from L at both 1 and 2 c per day. One possible way of proceeding is to assume that there are small terms of internal origin at these frequencies that are not part of the induction process, and to use conductivity models based on other daily variation terms to provide estimates of their amplitude and phase. Studies of local midnight values that extend the work of Malin (1977) on lunar magnetic variation midnight values should also help to determine the extent of magnetic variations of internal origin generated directly by the ocean dynamo. Work by Ashour and Price (1965) on night-time earth currents associated with the daily magnetic variations needs to be included in such studies.