Effect of ICME‐Driven Storms on Field‐Aligned and Ionospheric Currents From AMPERE and SuperMAG
Effect of ICME‐Driven Storms on Field‐Aligned and Ionospheric Currents From AMPERE and SuperMAG
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DOI：
10.1029/2022ja030423
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发表时间：
2022-08
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影响因子：
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通讯作者：
M. Pedersen;H. Vanhamäki;A. Aikio;C. Waters;J. Gjerloev;S. Käki;A. Workayehu
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作者：
M. Pedersen;H. Vanhamäki;A. Aikio;C. Waters;J. Gjerloev;S. Käki;A. Workayehu
这项研究通过考虑45个最小Dst ≤ −50 nT的事件来研究行星际日冕物质抛射（ICME）驱动的风暴的场向电流（FACs）和电离层等效电流。FACs和电离层等效电流的研究通过应用叠加历元分析的数据从AMPERE和SuperMAG与零历元（t0）集中在风暴主相的开始。亚暴发生的电流和次数在t0前开始增加3小时，在t0后约1小时达到最大值。在整个风暴主阶段，亚暴的电流和数量仍然很高，直到t0 + 14小时，它们开始慢慢放松回到安静的时间条件。根据t0前后的太阳风动压pdyn，将风暴分为两组。高pdyn风暴主要是由喷出物前面的鞘区驱动的。这些风暴有短的主相持续时间和较大的电流早在主相，最大化在t0 + 50分钟。低pdyn组包含的风暴，开始在磁云（MC）和逐渐增加的电流，最大化在t0 + 11小时，接近年底的风暴主相。在风暴主相的前4小时，鞘驱动风暴中的电流大于MC驱动风暴。罗素-麦克弗森效应对ICME驱动的风暴不太重要，只有44%的贡献，而高速流/流相互作用驱动的风暴则有82%。
This study investigates the field‐aligned currents (FACs) and ionospheric equivalent currents for interplanetary coronal mass ejection (ICME)‐driven storms by considering 45 events with a minimum Dst ≤ −50 nT. The FACs and ionospheric equivalent currents are studied by applying a superposed epoch analysis to data from AMPERE and SuperMAG with the zero epoch (t0) centered at the onset of the storm main phase. The currents and number of substorm onsets begin to increase 3 hr before t0 and maximizes about 1 hr after t0. The currents and number of substorm onsets remain high throughout the entire storm main phase, until at t0 + 14 hr they start to slowly relax back to quiet time conditions. The storms were separated into two groups based on the solar wind dynamic pressure pdyn around t0. High pdyn storms are mostly driven by the sheath region ahead of the ejecta. These storms have short main phase durations and larger currents early in the main phase which maximize at t0 + 50 min. The low pdyn group contains storms that start during the magnetic clouds (MC) and have gradually increasing currents that maximize at t0 + 11 hr, close to the end of the storm main phase. For the first 4 hr of the storm main phase, the currents in sheath‐driven storms are larger than for MC‐driven storms. The Russell‐McPherron effect is less important for ICME‐driven storms where only 44% have a contribution, compared to 82% of high speed stream/stream interaction driven storms.