Magnetospheric Multiscale Observations of the Off-equatorial Dipolarization Front Dynamics in the Terrestrial Magnetotail

We report the Magnetospheric Multiscale observations of dynamics at an off-equatorial dipolarization front (DF) in the Terrestrial Magnetotail. Three different plasma waves, namely electromagnetic ion cyclotron (EMIC) waves, lower hybrid drift waves, and electrostatic solitary waves (ESWs), associated with different electron pitch angle distributions were detected at different subregions of a single DF. It is interesting to note that the EMIC wave was linearly polarized, associating with a parallel current as a result of the antiparallel drift of electrons in the energy range of about 0.3-2 keV. These suggest that the wave was most likely to be locally generated. This generation could be explained by the current-driven kink-like instability due to the electron drift. The current-driven instabilities may dissipate the energy of the field-aligned current at the DF and thus play important roles in the magnetosphere-ionosphere coupling. On the other hand, the detected ESWs are interpreted as multidimensional electromagnetic electron holes (EHs) which are manifestations of several distinguishing features in electric and magnetic field perturbation. The EHs with a strong positive central potential suggested the likelihood of nonlinear behavior.