Two classes of equatorial magnetotail dipolarization fronts observed by
Magnetospheric Multiscale Mission: A statistical overview
Abstract
We carried out a statistical study of equatorial dipolarization fronts
(DFs) detected by the Magnetospheric Multiscale mission (MMS) during the
full 2017 Earth’s magnetotail season. We found that two DF classes are
distinguished: class I (74.4%) corresponds to the standard DF
properties and energy dissipation and a new class II (25.6%). This new
class includes the six DF discussed in Alqeeq et al. (2022) and
corresponds to a bump of the magnetic field associated with a minimum in
the ion and electron pressures and a reversal of the energy conversion
process. The possible origin of this second class is discussed. Both DF
classes show that the energy conversion process in the spacecraft frame
is driven by the diamagnetic current dominated by the ion pressure
gradient. In the fluid frame, it is driven by the electron pressure
gradient. In addition, we have shown that the energy conversion
processes are not homogeneous at the electron scale mostly due to the
variations of the electric fields for both DF classes.