A new type of density soliton, a dipole density soliton, as well as single dip and hump density solitons, were discovered in recent satellite observations of space plasmas. Moreover, these three kinds of density solitons are all associated with similar local electromagnetic fluctuations with Alfvén characteristics. This indicates that they originate from the same physical mechanism. We propose that the solitary plasma dipole vortex model can consistently account for these three kinds of density solitons, with the differences in their appearances attributed to the differences in the positions and directions at which the satellite crosses the solitary dipole vortex.

• Received 23 April 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.4346