Enhancement and modulation of cosmic noise absorption in the afternoon sector at subauroral location ( L = 5) during the recovery phase of 17 March 2015 geomagnetic storm
Enhancement and modulation of cosmic noise absorption in the afternoon sector at subauroral location ( L = 5) during the recovery phase of 17 March 2015 geomagnetic storm
复制标题
2015 年 3 月 17 日地磁风暴恢复阶段亚极光位置（L = 5）下午扇区宇宙噪声吸收的增强和调制
DOI：
10.1002/2017ja024226
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Behera J
中科院分区：
文献类型：
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作者：
Behera J
本研究的重点是在2015年3月17日圣帕特里克节开始的本太阳周期最大风暴的早期恢复阶段，在南极麦特里(L=5；CGM−62°S，55°E)产生强烈的宇宙噪声吸收。当地时间15-18时(当地时间14-17时)中央气象局的增强与风暴主要阶段的中央气象局增强的幅度相当。在此期间，CNA模式也在Pc5(2-7 MHz)范围内表现出振荡，并与同一频率范围内的地磁脉动同步。我们观察到CNA搏动的幅度与CNA产生的水平有很好的相关性。在麦特里附近的极光椭圆形附近观测到了高幅度的Pc5振荡。没有电磁离子回旋(EMIC)波，表明VLF波可能在降水中起作用。CNA产生强烈的原因主要是由嘶嘶驱动的亚相对论电子引起的降水。CNA增强事件恰好位于Tsurutani等人提出的黄昏等离子体层凸起区域内。(2015)。MLT 14-17期间，Maitri增强的向东电喷流的特征可能是如此大的CNA的另一个因素。为了建立麦特里地磁和CNA振荡之间的因果关系，用传递熵方法证实了地磁脉动对CNA的调制作用。
The present study has focused on the intense production of cosmic noise absorption (CNA) at Maitri, Antarctica (L= 5; CGM −62°S, 55°E) during the early recovery phase of the largest storm of the current solar cycle commenced on 17 March 2015 St. Patrick's Day. The enhancement of CNA during 15–18 UT(14–17 magnetic local time (MLT); MLT = UT − 1 at Maitri) was as large as the CNA enhancement occurred during the main phase of the storm. During this time the CNA pattern also exhibits oscillation in the Pc5 (2–7 mHz) range and is in simultaneity with geomagnetic pulsations in the same frequency range. We observed the amplitude of CNA pulsation is well correlated with the level of CNA production. High‐amplitude Pc5 oscillations were observed in the vicinity of auroral oval near Maitri. Absence of electromagnetic ion cyclotron (EMIC) waves is marked suggesting the possible role of VLF waves in precipitation. The reason for the intense CNA production is found to be the precipitation caused mainly by hiss‐driven subrelativistic electrons. The CNA enhancement event is located well inside the dusk plasmaspheric bulge region as suggested by Tsurutani et al. (2015). Signature of enhanced eastward electrojet at Maitri during 14–17 MLT could be an additional factor for such large CNA. In order to establish the cause and effect relationship between the geomagnetic and CNA oscillations at Maitri, transfer entropy method has been used, which confirmed the modulation of CNA by geomagnetic pulsations.