The Harris–Fadeev–Kan–Manankova family of exact two-dimensional equilibria is generalized to reproduce the slow decrease of the normal magnetic component in the tailward direction, and the magnetotail current sheet bending and shifting in the vertical plane, arising from the Earth dipole tilting and the solar wind nonradial propagation. The analytical solution is found to fit the empirical T96 model, especially, at distances beyond 10–15 Earth radii at high levels of magnetospheric activity.

Adaptive magnetospheric models based on THEMIS magnetic observations made at 6-9Re in the nightside magnetosphere are used to map the magnetically conjugate 30 and 80keV proton isotropy boundaries (IBs) to investigate the value of Kib=Rc/rc (magnetic curvature radius to particle gyroradius) in the neutral sheet at the IB generation place. For the most accurate mapping, the group Kib spread spans from 4 to 32; its median value is ~13, slightly larger than Kib8 expected for current sheet scatter.

A number of current systems exist in the Earth's magnetosphere. It is very difficult to identify local measurements as belonging to a specific current system. Therefore, there are different definitions of supposedly the same current, leading to unnecessary controversy. This study presents a robust collection of these definitions of current systems in geospace, particularly in the near-Earth nightside magnetosphere, as viewed from a variety of observational and computational analysis techniques.

Magnetic reconnection is a ubiquitous process that drives global-scale dynamics in plasmas. For reconnection to proceed, both ion and electrons must be unfrozen in a localized diffusion region. By analyzing in situ measurements, we show that the non-gyrotropic ion pressure is mainly responsible for breaking the ion frozen-in condition in reconnection. The reported non-gyrotropic ion pressure tensor can specify the reconnection electric field that controls how quickly reconnection proceeds.

We investigate the precipitated-to-trapped flux ratio patterns near the proton isotropy boundary (IB) using NOAA-POES observations. For 30 and 80keV proton energies, we found only 31% of events showing the dispersion pattern predicted by the non-adiabatic scattering in the tail current sheet. Most frequent pattern had no measureable IB energy dispersion (63%); structured IBs with a few Jprec/Jtrap dropouts were also usual (60%). Roles of current sheet and wave-induced scattering are discussed.