Wide-band observations of LF hiss at Frobisher Bay /L = 14.6/
Temporal and spectral characteristics of LF hiss recorded at Frobisher Bay from October 30 to November 18, 1972 and from June 27, 1974 to June 26, 1975 using a wide-band (0-100 kHz) receiver are reported and discussed. The hiss occurs in bursts of about 1 to 30 min duration with a bandwidth of at least 30 kHz centered in the 20-30 kHz range. Its frequency may extend downward below 10 kHz with decreasing intensity and upward to 100 kHz with increasing intensity. There is a strong diurnal peak of occurrence centered on 21 hours LMT. Some events simultaneously recorded by a 30-MHz rapid response riometer directly follow LF hiss bursts. Apparently some electron precipitation events produce hiss bursts only, others produce hiss and then a riometer event as the precipitation flux hardens, and others, too hard to produce hiss, produce riometer events only. An examination of the present data together with previous results (Jorgensen et al., 1962; Laaspere et al., 1976) leads to the conclusion that the precipitating electrons causing ground-observed LF hiss are more energetic and have smaller pitch angles than most auroral hiss observed in the topside atmosphere with an electric dipole antenna.