An interpretation of transverse whistlers

Recently, Carpenter and Dunckel [1965] reported a new type of whistler observed in the Alouette 1 satellite VLF recordings. It appeared in the frequency range of 1–8 kc/s and was observed late at night (2100 ∼ 0100 local time) from moderate to low latitudes (44° ∼ 30° dipole latitudes). One peculiar characteristic of this whistler is that the variation of time delay with frequency, observed at 1000-km altitude, is given by the sum of the Eckersley law time delay, characteristic of normal whistlers, and an additive correction term, as illustrated in Figure 1. The solid line in Figure 1a shows an example of the measured frequency versus time curve of one such whistler which was observed at 38°N geomagnetic latitude during the Alouette run of March 18, 1963.