Day‐to‐day changes in the latitudes of the foci of the Sq current system and their relation to equatorial electrojet strength

The latitudes of the foci of the Sq current systems over Australia and Japan are determined on a daily basis during the period from December 1989 to June 1990. The availability of a dense network of observatories in Australia during that time enabled a better determination in that region. Latitudinal movements of the foci are compared with the strength of the equatorial electrojet, and generally an increase in electrojet strength is accompanied with a poleward movement of the focus, especially in Japan. Some examples are noted where the foci in the two hemispheres move poleward or equatorward together from one day to the next, but this relationship was not found to be statistically significant. It is hard to disentangle effects due to other current systems such as Sqp from changes related to atmospheric tides. If some of the observed effects are due to tides, then the (2,3) and (2,4) semidiurnal modes are more likely contributors than the (2,2) mode.