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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >An empirical relationship between coronal mass ejection initial speed and solar wind dynamic pressure
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An empirical relationship between coronal mass ejection initial speed and solar wind dynamic pressure

机译：日冕物质抛射初始速度与太阳风动压之间的经验关系

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摘要

Interplanetary shocks that precede coronal mass ejections (CMEs) are mainly responsible for sudden impulses, which are characterized by a simple step-like increase in the horizontal H component. Such a magnetic field change has been explained as a compression of the magnetosphere by the passage of a sudden increase in the solar wind dynamic pressure. Strong compression of the dayside magnetopause could cause geosynchronous satellites to be exposed to solar wind environments where large fluctuations of the interplanetary magnetic field and highly energetic particles are present. In this study, we chose 26 event pairs consisting of a type II burst/CME occurring in conjunction with a sudden commencement/sudden impulse (SC/SI) whose solar wind, and Earth magnetic field data are available. We then investigated relationships among three physical properties (kinetic energy, directional parameter, and speed) of near-Sun CMEs, solar wind dynamic pressure, and SC/SI amplitude. As a result, we found that (1) the CME speed is more highly correlated with SC/SI amplitude than its kinetic energy and direction parameter; (2) by adopting the empirical relationship between solar wind dynamic pressure and amplitude of symmetric H (a steplike increase in the horizontal H component at low latitude), we could derive an empirical formula for the relationship between solar wind dynamic pressure near the Earth and the CME speed; (3) the CME speed has a linear relationship with the difference of magnetopause locations derived by using the model of Shue et al. (1998) at the subsolar point before and after the shock arrivals; (4) a fast CME greater than 1600 km s~(-1) could be a driver of the magnetopause crossing of a spacecraft at geosynchronous orbit. Our results show that the CME speed is an important parameter for early prediction of geosynchronous magnetopause crossing.
机译：冠状物质抛射（CME）之前的行星际冲击主要是造成突然的冲动，其特征是水平H分量以简单的阶梯状增加。这种磁场变化已被解释为由于太阳风动压力突然增加而导致的磁层压缩。日间磁层顶的强烈压缩可能会导致地球同步卫星暴露于太阳风环境中，在这种环境中，行星际磁场存在较大的波动，并且存在高能粒子。在这项研究中，我们选择了26个事件对，这些事件对包括II型爆发/ CME与突然的启动/突然冲动（SC / SI）一起发生，它们的太阳风和地球磁场数据均可用。然后，我们研究了近太阳CME的三个物理属性（动能，方向参数和速度），太阳风动压和SC / SI振幅之间的关系。结果，我们发现（1）CME速度与SC / SI振幅的相关性高于其动能和方向参数; （2）通过采用太阳风动压与对称H幅值（低纬度水平H分量呈阶梯状增加）之间的经验关系，可以推导出地球附近的太阳风动压与地面之间的关系的经验公式。 CME速度; （3）CME速度与通过Shue等人的模型得出的磁成顶位置的差异具有线性关系。 （1998）在冲击到达前后的次太阳点; （4）大于1600 km s〜（-1）的快速CME可能是地球同步轨道上航天器磁层顶穿越的驱动力。我们的结果表明，CME速度是早期预测地球同步磁层顶穿越的重要参数。

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