The position of dayside aurora (as measured from South Pole station in 1981) is compared to the interplanetary magnetic field Bz component and to the AE index. The results support our earlier work showing a close relationship with AE and little correlation with Bz. Two recent papers have presented data that purport to contradict this interpretation, claiming a dominant Bz correlation. A reanalysis of the data sets used in those papers does not support Bz dependence, and in fact reaffirms a close dependence on AE. We conclude that the position of the dayside cusp is largely controlled by substorm processes internal to the magnetosphere rather than by direct merging and erosion processes with the interplanetary field.
Journal of Geophysical Research