Discrete wave packets upstream from the earth and comets

Discrete wave packets are nearly monochromatic waves lasting several wave cycles which are frequently found on the leading edge of steepened low-frequency waves or shocklets upstream from the earth's bow shock. They apparently are whistler-mode waves which are generated as the shocklets steepen. These shocklets are blown back across the spacecraft so that the structure is observed in reverse order. Similarly appearing waves are present at comet Giacobini-Zinner. To determine if these waves are the same as those observed at earth a detailed comparison of the properties of the two sets of waves was undertaken. The waves have very similar amplitudes, durations, and directions of propagation.