A Statistical Study of Poleward Traveling Ionospheric Disturbances Over the African and American Sectors During Geomagnetic Storms
A Statistical Study of Poleward Traveling Ionospheric Disturbances Over the African and American Sectors During Geomagnetic Storms
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DOI：
10.1029/2021ja030162
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发表时间：
2022-03
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通讯作者：
J. Habarulema;Golekamang P. Thaganyana;Z. Katamzi‐Joseph;E. Yizengaw;M. Moldwin;C. Ngwira
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作者：
J. Habarulema;Golekamang P. Thaganyana;Z. Katamzi‐Joseph;E. Yizengaw;M. Moldwin;C. Ngwira
我们提出了2010-2018年期间发生的磁暴期间起源于地磁赤道附近的旅行电离层扰动（TID）的统计结果。根据Kp > 4和Dst ≤ −50 nT的风暴判据，分析了全球导航卫星系统（GNSS）在40°S-60°N纬度范围内、20°-40 ° E经度范围内和50°-70 ° W经度范围内对非洲和美洲区域的总电子含量扰动。虽然非洲扇区的北方半球部分的数据覆盖范围有限，但结果表明，在分析期间，发射的TID与其原点的纬度距离不超过20°-25°。在极向发射的TID主要限制在绕地磁赤道±20° ~ 30 °范围内的美国扇区上观察到统计上类似的结果。在有数据的情况下，大多数情况与电离层电动力学的变化有关，特别是赤道电射流的增强，尽管还有其他观测结果不能用赤道电射流的变化来解释。这表明，可能有其他的物理机制，在发射TID在地磁赤道扰动条件下发挥作用。一个重要的结果是，已经发现大规模和中等规模的TID分别主要发生在地磁风暴的主要阶段和恢复阶段，至少在非洲部分。
We present statistical results of traveling ionospheric disturbances (TIDs) with origin near the geomagnetic equator during geomagnetic storms that occurred within the period of 2010–2018. Based on storm criteria of Kp > 4 and Dst ≤ −50 nT, we have analyzed total electron content perturbations derived from Global Navigational Satellite Systems observations within a latitude range of 40°S–60°N and longitude ranges of 20°–40°E and 50°–70°W representing the African and American sectors. Although the northern hemispheric part of the African sector has limited data coverage, results show that the launched TIDs do not exceed the latitudinal distance of 20°–25° from their origin during the analyzed period. A statistically similar result is observed over the American sector with launched poleward TIDs constrained largely within ±20°–30° around the geomagnetic equator. Where data are available, majority of these cases are linked to changes in ionospheric electrodynamics, especially the enhancement of equatorial electrojet (EEJ), although there are other observations that are not explained by EEJ variability. This indicates that there may be other physical mechanisms that play a role in launching TIDs at the geomagnetic equator during disturbed conditions. An important result is that large‐scale and medium‐scale TIDs have been found to occur predominantly during the main and recovery phases of geomagnetic storms, respectively, at least over the African sector.