A study of auroral absorption events at the South Pole: 2. Conjugate properties

At South Pole and Frobisher Bay, a magnetically conjugate pair of high-latitude stations, the auroral absorption events observed with riometers have many points of similarity. Yet there are also some significant differences, which have been brought out in this study by a detailed, event-for-event comparison. First, systematic changes have been detected in the relative intensity of the events, and they are such that the absorption tends to be relatively greater in local winter; there is also a diurnal change in the relative intensity. Second, there is good evidence that the event maximums appear in the conjugate regions at slightly different times; for individual events the time differences are correlated with the relative intensities. The results suggest that auroral absorption might be either produced or modulated by hydromagnetic disturbances propagating in the magnetosphere.