High-speed jets (HSJs) are transient structures that are abundant in the Earth's magnetosheath, and they have been of particular interest to the space physics community for more than a decade. A high-speed jet could have a dynamic pressure greater than that of the ambient solar wind in the magnetosheath. This dynamic pressure, though not typically, can even surpass that of the upstream solar wind. Thus, a high-speed jet can have a strong impact on the magnetopause (

The gradients of physical quantities play important roles in the dynamic evolution of space plasmas. For example, the first-order gradient of electromagnetic fields balances their temporal variations as well as their sources (charge density and current density); the linear gradient of certain physical quantities (magnetic field, thermal pressure, etc.) can also drive the drift motions of charged particles in electromagnetic fields. The linear gradient of physical quantities can be estimated from 4-point in-situ measurements with first-order accuracy, and many estimators have already been developed (

No abstract

Electromagnetic fields are omnipresent in space. They control the motion of plasmas, and the transportation, release, and transformation of energy in space, and thereby are the key driver of space weather hazards. Charges and electric currents (flows of charged particles) source the electromagnetic field, and therefore the distribution and motions of charges determine its form. Charge separations occur in electric double layers, which exist commonly in space plasmas (Akasofu, 1981;Block, 1975;Raadu, 1989). Net charges can appear in plasma boundary layers (Parks, 1991), for example, the magnetopause boundary layers and Alfvén layers (Hasegawa & Sato, 1989). Charge separations can also occur during ambipolar diffusion processes (

No abstract