Geomagnetic negative sudden impulse due to a magnetic cloud observed on May 13, 1995
Geomagnetic negative sudden impulse due to a magnetic cloud observed on May 13, 1995
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DOI：
10.1029/2000ja900055
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发表时间：
2000-08
影响因子：
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通讯作者：
T. Takeuchi;T. Araki;H. Luehr;O. Rasmussen;J. Watermann;D. Milling;I. Mann;K. Yumoto;K. Shiokawa;T. Nagai
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文献类型：
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作者：
T. Takeuchi;T. Araki;H. Luehr;O. Rasmussen;J. Watermann;D. Milling;I. Mann;K. Yumoto;K. Shiokawa;T. Nagai
对1995年5月13日观测到的一次地磁负突冲（SI−）进行了研究，利用ETS VI和GOES 7在磁层和地面地磁观测网的磁场数据。SI−是由嵌入在密度增强区的磁云前边界的太阳风动压突然下降引起的。Kakioka地磁观测站（磁纬26.9°，磁经208.3°）的振幅为26 nT，下降时间为10 min。虽然SI−被认为是地磁正突冲（SI+）或突然开始（SC）的镜像，但我们发现SI−的极化分布与SC一致。我们认为，双涡旋电离层电流系统的纵向运动对SC和SI−的极化产生起主导作用。我们还讨论了太阳风不连续点撞击磁层的角度与地磁响应之间的关系。
A geomagnetic negative sudden impulse (SI−) observed on May 13, 1995, was examined using magnetic field data from ETS VI and GOES 7 in the magnetosphere and ground geomagnetic observation networks. The SI− was caused by a sudden decrease in the solar wind dynamic pressure at the front boundary of a magnetic cloud embedded in a density enhancement region. The amplitude and the fall time at Kakioka geomagnetic observatory (magnetic latitude 26.9°, magnetic longitude 208.3°) were 26 nT and 10 min, respectively. Although SI− has been considered to be the mirror image of geomagnetic positive sudden impulse (SI+) or sudden commencement (SC), we found the polarization distribution of the SI− consistent with that of SC. We suggest that the contribution from the longitudinal movement of a twin-vortex ionospheric current system is dominant to produce the polarization of SC and SI−. We also discuss the relationship between the angle at which discontinuities in the solar wind impinge upon the magnetosphere and the geomagnetic response.