A comparison of Sq analyses with model calculations

Three analyses of Sq are examined in detail. The analyses separate Sq into external and internal parts. The external part is used as an inducing field in a model earth consisting of a perfectly conducting inner sphere (conductosphere) surrounded by a thin non-uniformly conducting shell representing in some detail the distribution of oceans and continents. The calculated induced part is compared to the internal part deduced in the analysis. The comparison is poor and the reason is shown to be that the magnetic observatories are not located in regions influenced by the main induced oceanic currents. It is further shown that some Sq analyses are unacceptable on physical grounds.