A compressed and oscillating magnetotail observed by TC1 during the enhancement and fluctuation of solar wind dynamic pressure
【摘要】：During the interval from 0615-0730UT on 24 August 2005, the near-Earth magnetotail displayed multiple responses to the combined changes in solar wind dynamic pressure and interplanetary magnetic field (IMF). The magnetotail was highly compressed by a strong interplanetary shock due to the dynamic pressure enhancement (~15nPa), and the large shrinkage of magnetotail made a northern lobe/mantle move inward to the position of inbound TC1 satellite that was initially in the plasma sheet. Meanwhile, the dynamic pressure fluctuation behind the shock drove the quasi-periodic oscillations of the magnetopause, lobe-mantle boundary and geomagnetic field at the same frequencies, one dominant frequency is around 3mHz and the other is around 5mHz. The oscillation of the lobe-mantle boundary caused the alternate entries of TC1 into the northern lobe and the plasma mantle. In contrast to a single squeezed/deformed magnetotail by a solar wind discontinuity moving tailward, the compressed and oscillating magnetotail can better indicate the dynamic evolution of magnetotail when solar wind dynamic pressure increases and fluctuates remarkably. Furthermore, it is found that the considerable oxygen ions (O+) appeared in the lobe after the southward turning of IMF.