Аннотация:We summarize the results demonstrating the existence of surrounding the Earth plasma population having the form of plasma ring at geocentric distances from 6-7RE till magnetopause near noon and till ~10-12RE near midnight. Plasma characteristics of the ring are near to plasma sheet proper. However in difference with plasma sheet proper, where the magnetic field lines are stretched in the antisolar direction, magnetic field lines in the ring have dipole like characteristics during quite time. Plasma pressure in the ring is larger than in the plasma sheet proper. Transverse currents in the surrounding the Earth plasma ring are closed inside the magnetosphere. Nightside part of the ring was previously selected as near the Earth plasma sheet. Magnetic field lines of the plasma sheet proper are stretched and its transverse currents are closed by magnetopause currents. It is a rather turbulent region with large fluctuations of plasma velocity and magnetic field filled by bursty bulk flows (BBF), thin current sheets, beams ets.
Plasma pressure at geocentric distances >6-7Re is near to isotropic. Such feature gives the possibility to use plasma pressure as the natural marker of the magnetic field line as in the condition of the magnetostatic equilibrium plasma pressure has the constant value along the field line. We compare values of plasma pressure measured at low latitudes by DMSP satellites and plasma pressure measured at the equatorial plane. We show that the main part of the discrete auroral oval is mapped to the surrounding the Earth plasma ring. Such feature explains the existence of quite comparatively stable auroral arcs inside the oval. Mechanism of arc formation is discussed. We show that the obtained picture of auroral domain mapping is rather useful for the explanation of different events including appearance of electrons-"killers".