Counter‐Electrojet Occurrence as Observed From C/NOFS Satellite and Ground‐Based Magnetometer Data Over the African and American Sectors
Counter‐Electrojet Occurrence as Observed From C/NOFS Satellite and Ground‐Based Magnetometer Data Over the African and American Sectors
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DOI：
10.1029/2019sw002236
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发表时间：
2019-07
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通讯作者：
J. Habarulema;Gabrielle Lefebvre;M. Moldwin;Z. Katamzi‐Joseph;E. Yizengaw
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文献类型：
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作者：
J. Habarulema;Gabrielle Lefebvre;M. Moldwin;Z. Katamzi‐Joseph;E. Yizengaw
基于通信和导航中断预报系统（C/NOFS）垂直离子等离子体漂移（相当于高度约 400 km 处的垂直 E×B）和地面磁力计的当地白天（0700-1700 LT）观测，对 2008-2014 年非洲和美洲地区的反电喷射发生（CEJ）进行了分析。使用安静时间（Kp≤3）数据，根据当地时间和季节依赖性确定两个数据集之间的差异和/或相似之处。首次表明，C/NOFS 卫星数据在识别所有季节 CEJ 发生时与磁力计观测结果一致。然而，C/NOFS 卫星数据显示几乎所有季节的 CEJ 发生率都较高。就当地时间而言，C/NOFS 卫星在美洲和非洲地区观测到的 CEJ 事件比磁力计观测的要多，平均分别约为 20% 和 40%，尽管两个数据集都显示了 CEJ 识别的相似趋势。因此，当空间天气事件发生时，重要的是首先确定赤道地区东向电场的原始变化性质和/或大小，然后将由此产生的变化归因于太阳风-磁层和电离层耦合过程，因为CEJ事件即使在安静条件下也可能出现。
An analysis of the counter‐electrojet occurrence (CEJ) during 2008–2014 is presented for the African and American sectors based on local daytime (0700–1700 LT) observations from the Communications and Navigation Outage Forecasting System (C/NOFS) vertical ion plasma drift (equivalent to vertical E×B at an altitude of about 400 km) and ground‐based magnetometers. Using quiet time (Kp≤ 3) data, differences and/or similarities between the two data sets with reference to local time and seasonal dependence are established. For the first time, it is shown that C/NOFS satellite data are consistent with magnetometer observations in identifying CEJ occurrences during all seasons. However, C/NOFS satellite data show higher CEJ occurrence rate for almost all seasons. With respect to local time, C/NOFS satellite observes more CEJ events than magnetometer observations by average of about 20% and 40% over the American and African sectors, respectively, despite both data sets showing similar trends in CEJ identification. Therefore, when a space weather event occurs, it is important to first establish the original variability nature and/or magnitude of the eastward electric field in equatorial regions before attributing the resulting changes to solar wind‐magnetosphere and ionosphere coupling processes since CEJ events can be present even during quiet conditions.