Small-scale solitary wave pulses observed by the Ulysses magnetic field experiment

[ 1] We present here a new class of isolated structure observed in interplanetary space. Events in this class consist of short-duration increases in the magnetic field magnitude and an associated rotation in the magnetic field direction, with a duration of the order of 30 s. After surveying the entire 14-year high-resolution ( 1 vector sample per 1 or 2 s) Ulysses magnetometer data set, 33 candidate events were found. We present some preliminary analysis regarding the observational properties of these events. Of primary interest are the results of variance analysis of each event. These give insights into the spatial structure and, if there is relative velocity to the ambient solar wind, propagation direction of each event. We find that the minimum variance direction is well defined and tends to align to the radial (RTN system) direction, with only a modest trend to an alignment to the ambient magnetic field. We have determined an approximate scale size of about 30 ion inertial lengths for the events. We compare the observations to a soliton model and show that current models, although strikingly similar in some respects, do not adequately explain the observations.