A STUDY OF AURORAL ABSORPTION AT 30 MC/S

Abstract

The occurrence of auroral absorption, as observed over a two-year period at six Canadian stations extending in a north–south line between Resolute Bay and Ottawa, is discussed. On the average, the zone of maximum occurrence of auroral absorption is located near 63° geomagnetic latitude but tends to shift several degrees farther south during periods of strong magnetic activity. The occurrence falls off rapidly to the north of the zone maximum and there is no indication of an inner zone of auroral absorption activity. Contour plots are used to illustrate occurrence as a function of geomagnetic latitude and mean geomagnetic time. The resulting pattern shows a principal maximum near 0800 hours and a secondary maximum an hour or two before geomagnetic midnight. The pattern appears to fit the theoretical model of high-latitude disturbances as developed by Axford and Hines, and the possibility is discussed that there are two distinct phases in this disturbance pattern that correspond to the two diurnal maxima in the auroral absorption data.