Effect of Tailward Flows From the Ionosphere on the Near-Earth Magnetic Field

Tailward flows are often observed in the near-Earth magnetotail by TC-1 satellite during quiet time and substorm active period. The statistical studies show that the perpendicular component of the tailward flow will leads to stretching of magnetic field lines. Due to the tailward flow, the Bx component of the magnetic field distinctly increases or the magnetic field geometry becomes tail-like from dipolar-like. The magnetic field is recovered and back to dipole-like structure when plasma flow is reversed. Along with magnetic field stretch, it is found that both temperature anisotropy and ion temperature decrease at the same time. During the period of the magnetic field recovering dipolar- like, the ion temperature rapidly increases and the temperature becomes anisotropy associated with the release of the magnetic energy. From the observations, it is also shown that the tailward flow causes an enhancement of By component. The results from the TC-1 satellite indicate that the tailward flow from the ionosphere has an important effect on the near-earth magnetotail.