Abstract. We study the average shape and position of the magnetotail neutral sheet based on magnetic field data obtained by Cluster, Geotail, TC-1, and THEMIS from the years 1995 to 2013. All data in the aberrated GSM (geocentric solar magnetospheric) coordinate system are normalized to the same solar wind pressure 2 nPa and downtail distance X ∼ −20R E . Our results show characteristics of the neutral sheet, as follows. (1) The neutral sheet assumes a greater degree of curve in the YZ cross section when the dipole tilt increases, the Earth dipole tilt angle affects the neutral sheet configuration not only in the YZ cross section but also in the XY cross section, and the neutral sheet assumes a more significant degree of tilt in the XY cross section when the dipole tilt increases. (2) Counterclockwise twisting of the neutral sheet with 3.10 • is observed, looking along the downtail direction, for the positive interplanetary magnetic field (IMF) B Y with a value of 3 to 8 nT, and clockwise twisting of the neutral sheet with 3.37 • for the negative IMF B Y with a value of −8 to −3 nT, and a northward IMF can result in a greater twisting of the near-tail neutral sheet than southward. The above results can be a reference to the neutral sheet model. Our large database also shows that the displaced ellipse model is effective to study the average shape of the neutral sheet with proper parameters when the dipole tilt angle is larger (less) than 10 • (−10 • ).

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Sub-ion magnetic holes are rich in the terrestrial plasma sheet and magnetosheath. Here, we statistically investigate 60 sub-ion magnetic holes in the solar wind at 1 AU using the high-resolution data measured by the Magnetospheric Multiscale mission. We find that they are observed with a duration of 0.1-0.5 s, and the lengths of their cross-section are~0.1-0.6 ion gyroradius. These structures prefer to occur in the slow solar wind with a weak ambient magnetic field strength. They also prefer to occur in the marginally mirror stable or unstable environments. Electron vortices as well as an enhancement of the electron perpendicular temperature and electron fluxes at~90°pitch angle tend to be observed inside some magnetic holes with a large ambient magnetic field strength. By contrast, there are no clearly observational electron vortices as well as the electron fluxes at~90°pitch angle inside some magnetic holes with a weak ambient magnetic strength. The current density with a value of~10-50 nA/m 2 reveals that the corresponding maximum electron velocity is <10 km/s inside some magnetic holes, lower than the level of the observational electron velocity noise, which prevents the detection of the weak electron vortex. We suggest that electron vortices exist inside all the sub-ion magnetic holes in the solar wind. The generation of these sub-ion magnetic holes can be explained by the electron magnetohydrodynamics soliton and the electron vortex magnetic hole.

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We statistically examine the characteristic scaling features of fluctuations in the dayside Venusian magnetosheath downstream of different types, quasi-parallel (Q ∥ ) and quasi-perpendicular (Q ⊥ ), of bow shock based on Venus Express data. We found that magnetic fluctuations have different characteristic scaling features downstream of Q ∥ and Q ⊥ bow shocks. Although the Venusian dayside magnetosheath is much thinner than the Earth magnetosheath, fully developed turbulence can be still observed downstream of the Q ∥ bow shock, while the turbulence is not dominant downstream of Q ⊥ bow shock. The type of bow shock plays an important role in the characteristic scaling features of downstream magnetic fluctuations. That means that the Q ∥ IMF might be a source of the turbulence in Venusian magnetosheath.