Abstract
Electrostatic solitary waves (ESWs) are a type of nonlinear time-domain
plasma structure (TDS) generally defined by bipolar electric fields and
propagation parallel to the local magnetic field. Formation mechanisms
for TDSs in the magnetosphere have been studied extensively and are
associated with plasma boundary layers and the braking of bursty bulk
flows (BBFs). However, the rapid timescales over which these TDSs occur
(< 2 ms) make them infeasible to count by eye over large time
periods. Furthermore, high-cadence data are not always available. The
Solitary Wave Detector (SWD) on NASA’s Magnetospheric Multiscale (MMS)
mission quantifies the occurrence and amplitude of TDS throughout the
constellation’s orbit; analysis of burst (65 kS/s) parallel electric
field data indicates that the SWD captures appx. 60% of all bipolar TDS
encountered in the tail region, enabling large-scale examination of
their occurrence. Maps of TDS occurrence rates during several years of
the MMS mission were generated from SWD data, showing enhanced TDS
density in the tail region between 6-9 Re; enhance occurrence in or near
shocks; and an unexpected enhancement in the dawn side of the tail and
in the radiation belt.