Statistics of the Intense Current Structure in the Dayside Magnetopause
This paper presents a comprehensive study of the intense current
structure (ICS) at the dayside magnetopause, by using the
high-resolution data from the Magnetospheric Multiscale (MMS) mission.
About 3,600 ICSs with current density exceeding 1.2 μA/m2 have been
detected during phase 1a and 1b within the magnetopause boundary layer
(MBL). We find that most ICSs have a temporal duration of less than 1
second and thickness of less than one ion inertial length. The number of
ICSs decreases with the thickness increasing from the electron-scale to
the ion-scale. The occurrence rate of the ICS is relatively higher close
to Earth and in the dusk sector near the meridian, probably caused by
the large solar wind dynamic pressure. In a local boundary normal
coordinate system, the occurrence rate is higher on the magnetosheath
side. For most ICSs, the current is carried by electrons. The
perpendicular current is larger than the parallel current for more ICSs.
The energy conversion J·E is primarily through the perpendicular current
and electric field, while the non-ideal energy conversion J·E’ is mainly
dominated by the parallel component. ICSs provide much stronger energy
conversion and dissipation compared to the ambient plasma in the MBL.
This study improves our understanding of the characteristics of the ICS
and its role in solar wind-magnetosphere coupling.