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arXiv 1402.0927physics.space-ph
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2005年1月21日期间极度压缩的magnetosphere异常动力学magnetic storm

Anomalous dynamics of the extremely compressed magnetosphere during 21 January 2005 magnetic storm

A. V. Dmitriev, A. V. Suvorova, J. -K. Chao, C. B. Wang, L. Rastaetter, M. I. Panasyuk, L. L. Lazutin, A. S. Kovtyukh, I. S. Veselovsky, I. N. Myagkova

摘要:

分析了2005年1月21日异常磁暴期间昼侧磁层和质子辐射带的动力学特征。我们发现,在1712 - 2400 UT的风暴期间,由于强烈的压缩,太阳下磁层顶持续位于地球同步轨道内。在1846 ~ 2035 UT期间,当快速爆发的暗条的稠密等离子体产生太阳风动压Pd时,压缩非常强烈,峰值超过100 nPa,并首次在地球同步轨道上观测到上游太阳风,观测时间长达2小时。在极端压缩作用下,L > 5的外磁层被向内推挤,能量为几十keV的外辐射带粒子向地球运动,在L < 4的内磁层被加速并聚集,产生了寿命极长的强环电流。的观察结果进行了比较,各种经验和第一原理模型的预测。当最小磁层顶距离为~ 3Re时,所有模型都不能预测极端压缩下的磁层动力学。模型预测和观测之间的不一致可能是由于极端日光层条件造成的等离子体测量失真,这些条件包括非常快的太阳风流(~1000 km/s)和强烈的太阳高能粒子通量。我们推测,如果假设太阳风中He丰度大于20%,则磁层的异常动力学可以很好地被模型所描述,这对于爆发的暗条是很合适的,并且与星团测量中He/H比的上限27%相一致。

英文摘要:

Dynamics of the dayside magnetosphere and proton radiation belt was analyzed during unusual magnetic storm on 21 January 2005. We have found that during the storm from 1712 to 2400 UT, the subsolar magnetopause was continuously located inside geosynchronous orbit due to strong compression. The compression was found to be extremely strong from 1846 to 2035 UT when the dense plasma of fast erupting filament produced the solar wind dynamic pressure Pd peaked up to >100 nPa and, in the first time, the upstream solar wind was observed at geosynchronous orbit during almost 2 hours. Under the extreme compression, the outer magnetosphere at L > 5 was pushed inward and the outer radiation belt particles with energies of several tens of keV moved earthward, became adiabatically accelerated and accumulated in the inner magnetosphere at L < 4 that produced the intensified ring current with an exceptionally long lifetime. The observations were compared with predictions of various empirical and first principles models. All the models failed to predict the magnetospheric dynamics under the extreme compression when the minimal magnetopause distance was estimated to be ~3 Re. The inconsistencies between the model predictions and observations might result from distortions of plasma measurements by extreme heliospheric conditions consisting in very fast solar wind streams (~1000 km/s) and intense fluxes of solar energetic particles. We speculated that anomalous dynamics of the magnetosphere could be well described by the models if the He abundance in the solar wind was assumed to be >20%, which is well appropriate for erupting filaments and which is in agreement with the upper 27% threshold for the He/H ratio obtained from Cluster measurements.

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