WHISTLER-LIKE PULSATION EVENTS IN THE FREQUENCY RANGE 20 TO 200 Hz

A class of events, sweeping down in frequency, occurring between 20 and 200 Hz, were observed for the first time. The observing site is at Poker Flat, Alaska, 65 degrees N. Characteristics include a daytime diurnal maximum, an apparent seasonal minimum in winter, a tendency for maximum occurrences on magnetically quiet days, and a typical event duration of similar to 1 minute. The events occur at the same frequencies as a type of hiss observed on OGO-5 (Kivelson and Russell, 1973) and a class of events observed on Injun 5 called 'lion's roar' (Gurnett and Frank, 1972), but the spectral form of the events observed on the ground is quite different from either of those types.