Discrete wave packets upstream from the Earth and comets


  • G. Le,

  • C. T. Russell,

  • E. J. Smith


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 we have undertaken a detailed comparison of the properties of the two sets of waves. The waves have very similar amplitudes, durations, and directions of propagation. Thus we feel that the source mechanism for the two phenomena must be the same, i.e., wave steepening.