Currents at the subsolar low shear magnetopause

A model of a current system at the subsolar low shear magnetopause is suggested. This model is valid under certain conditions of an overlap of magnetosheath and magnetospheric populations. The current system contains two current layers created by two different sorts of ions (magnetospheric and magnetosheath) at their boundary. For northward interplanetary magnetic field, the magnetopause azimuthal currents in these layers are antiparallel: a current carried by magnetosheath ions flows from noon to dusk, and a current created by magnetospheric ions is directed from noon to dawn. In this case, due to the rotation of magnetic field caused by two antiparallel currents, a negative spike in the northward component of the magnetic field Bz arises at the magnetopause. This specific feature allows us to define the magnetopause location in the case of a low magnetic shear, when the identification of the magnetopause is not obvious. A goal of the paper is to explain the main physical reason leading to the described current system. This reason is a change in all plasma parameters and magnetic field strength at the subsolar magnetopause. Model estimations allow us to compare the obtained results with observations and with existing theoretical models.