Observations of the Aurora Australis at New Zealand Antarctic stations during IGY

Intensive auroral observations at Scott Base and Hallett Station during IGY indicate that auroral activity is higher than has previously been estimated at these latitudes. The distribution of auroral activity is not simple; it appears to consist of two superimposed systems, one of isolated rays and the other of arcs and bands, symmetrical about different axes. Orientation of the principal arcs fits a zone which takes account of the nondipole field better than one based on the centered geomagnetic dipole, though the auroral frequencies conflict with this. Auroral activity increases with local geomagnetic disturbance at Hallett Station, but at Scott Base there is negligible increase in the probability of auroral occurrence until K = 5. However, the diurnal variation of auroral frequency, which is bimodal with the primary maximum at 04 hours local time and the secondary maximum at 17 hours local time, does not appear to be related to the diurnal trend of local geomagnetic disturbance, but the principal auroral events inside the zone seem to coincide with the principal magnetic events in the Stagg transition zone. The only characteristic colored form observed, a pale red glow on the horizon, is associated with high magnetic activity and ionospheric absorption. The latitude of auroral forms decreases with increase in K index. The results are compared with those of previous expeditions to Ross Island and Cape Adare.