The 3-dimensional characteristics of the magnetic field lines and the non-adiabatic region in the magnetosphere

In this paper, the 3-dimensional configurations of the non-adiabatic region and the magnetic field lines (MFLs) in the magnetosphere are studied based on the Tsyganenko magnetic field model. According to the parameter δ = dB/B, the magnetosphere can be divided into the adiabatic and non-adiabatic region. A thin non-adiabatic region has been found in the near tail region, which moves toward to the Earth during the geomagnetic disturbance. Pitch angle scattering occurs when particles go through the non-adiabatic region, which is expected as the source region of the precipitating particles. Moreover, by investigating the 3-dimensional configurations of MFLs, we find that MFLs remain in the noon meridian plane if their foot prints are in the noon meridian plane; but leave the foot print plane and are swept tailward if their foot prints are not in the noon meridian plane. The characteristics of the MFLs suggest that the precipitation region is almost in the nightside region, centered near midnight.