Propagation of the preliminary reverse impulse of sudden commencements to low latitudes
Propagation of the preliminary reverse impulse of sudden commencements to low latitudes
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DOI：
10.1029/2001ja900071
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发表时间：
2001-09
影响因子：
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通讯作者：
P. Chi;C. Russell;J. Raeder;E. Zesta;K. Yumoto;H. Kawano;K. Kitamura;S. Petrinec;V. Angelopoulos;G. Le;M. Moldwin
中科院分区：
文献类型：
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作者：
P. Chi;C. Russell;J. Raeder;E. Zesta;K. Yumoto;H. Kawano;K. Kitamura;S. Petrinec;V. Angelopoulos;G. Le;M. Moldwin
人们认为，突发事件（SC）现象的初始反向脉冲（PRI）同时发生在地面上的不同位置。一个流行的解释是，PRI传播通过地球电离层波导在35个地面磁强计站在1998年9月24日的SC事件，并发现在PRI的到达时间的明显差异。我们计算的MHD波的传播时间从磁层的第一次压缩的位置低纬度地面站，并发现与观测到的PRI到达时间很好的协议。我们的计算还表明，波前是严重扭曲的磁层的不均匀性和高纬度和低纬度观测之间的PRI到达时间的小差异不能是一个指标的超阿尔文传播。我们还发现，高纬度PRI可以诱导附近纬度的电离层电流涡，电流涡的运动可以影响高纬度PRI的到达时间。
It has been thought that the preliminary reverse impulse (PRI) of the sudden commencements (SC) phenomena occurs simultaneously on the ground at different locations. A popular explanation is that the PRI propagates through the Earth-ionosphere waveguide at the 35 ground magnetometer stations during the SC event on September 24, 1998, and found clear differences in the arrival time of PRI. We calculated the MHD wave propagation time from the location of the first compression of the magnetosphere to the low-latitude ground stations and found good agreement with the observed PRI arrival times. Our calculation also indicates that the wavefront is seriously distorted by the inhomogeneity of the magnetosphere and the small difference in PRI arrival time between high-latitude and low-latitude observations cannot be an indicator of a super-Alfvenic propagation. We also found implications that high-latitude PRIs can be induced by the vortex of ionospheric currents at nearby latitudes, and the motion of the current vortex can affect the arrival time of high-latitude PRIs.