Morphology of the equatorial ionization anomaly in Africa and Middle East due to a sudden stratospheric warming event
Morphology of the equatorial ionization anomaly in Africa and Middle East due to a sudden stratospheric warming event
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平流层突然变暖事件导致非洲和中东赤道电离异常的形态
DOI：
10.1016/j.jastp.2019.01.006
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发表时间：
2019
影响因子：
1.9
通讯作者：
Kotoye A.
中科院分区：
文献类型：
--
作者：
Bolaji O.S.;Oyeyemi E.O.;Jimoh O.E.;Fujimoto A.;Doherty P.H.;Owolabi O.P.;Adeniyi J.O.;Falayi E.O.;Abe E.;Kaka R.O.;Kotoye A.
利用从非洲和中东 18 个全球定位系统 (GPS) 接收器推导出来的总电子含量 (TEC) 数据，我们研究了 2009 年平流层突然变暖 (SSW) 事件之前、期间和之后的赤道电离异常 (EIA) 形态及其潜在变化。在 SSW 事件发生前的大部分时间里，观察到南部 EIA 波峰强于北部 EIA 波峰，而 EIA 波谷在这些 SSW 诱发阶段后明显消失。除了在 SSW 峰值阶段观察到半球 EIA 波峰的显着损耗外，我们还观察到横跨北部 EIA 波峰的昼夜变化。这种背景昼夜特征被认为是在 SSW 峰值阶段将更多血浆输送到北半球而牺牲南半球的部分原因。其结果是，与南半球的单一波峰相比，北半球的中午前和中午后波峰更高。与之前的模型和实验报告相反，电离层 TEC 的减少是由于 SSW 峰值相位引起的半日变化造成的，我们的结果表明，昼夜变化分别导致了 E 区和 F2 区上部的 EEJ 强度和 TEC 降低。在南部中纬度地区，在 SSW 下降阶段，潜在的日变化引发了 TEC 的增加。
Using total electron content (TEC) data deduced from 18 Global Positioning System (GPS) receivers in Africa and Middle East, we investigated the morphology of the equatorial ionization anomaly (EIA) and its underlying variations before, during and after the 2009 sudden stratospheric warming (SSW) event. A southern EIA crest stronger than the northern EIA crest was observed for most of the days before the SSW event, while the EIA troughs were significantly obliterated after these SSW induced phases. In addition to the observed marked depletion of the hemispheric EIA crests during the SSW peak phase, we observed a terdiurnal variation straddling the northern EIA crests. This background terdiurnal signature is suggested to be partly responsible for the transport of more plasma to the northern hemisphere at the expense of southern hemisphere during the SSW peak phase. The consequences are higher pre-noon and post noon crests in the northern hemisphere compared to a single crest in the southern hemisphere. Contrary to previous modeling and experimental reports that the reductions in ionospheric TEC are due to semidiurnal variations resulting from the SSW peak phase, our results show that a terdiurnal variation was responsible for reducing the EEJ strength and TEC at the E-region and F2-region's topside, respectively. At the southern middle latitudes, an underlying diurnal variation was seen to initiate an increment in TEC during the SSW descending phase.