Longitudinal structure of the equatorial ionosphere: Time evolution of the four-peaked EIA structure
Longitudinal structure of the equatorial ionosphere: Time evolution of the four-peaked EIA structure
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DOI：
10.1029/2007ja012455
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发表时间：
2007-12
影响因子：
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通讯作者：
Chien-Hung Lin;C. Hsiao;Jann‐Yenq Liu;C. Liu
中科院分区：
文献类型：
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作者：
Chien-Hung Lin;C. Hsiao;Jann‐Yenq Liu;C. Liu
[1]利用FORMOSAT-3/COSMIC （F3/C）卫星星座观测了赤道电离层24 h局地周期的纵向结构。通过对2006年9月和10月F3/C掩星观测数据的综合分析，获得了恒定地方时全球电离层总电子含量（TEC）图（地方时TEC图，简称LT图），用于监测赤道电离层四峰纵向结构的发展和沉降。从LT图上看，4峰结构在0800-1000 LT开始发育，在1200-1600 LT最突出。纵向结构在2200-2400 LT后开始下沉，0400-0600 LT后逐渐消失。除了TEC外，电离层峰值高度也表现为4峰纵向结构，其变化与TEC在白天非常相似。电离层高峰高度的四峰结构在夜间是看不出来的。利用电离层TEC和峰值海拔的全球地方时图，我们比较了电离层纵向结构的时间变化与经验模型得出的E × B漂移的变化。我们的观测结果与赤道等离子体喷泉受E3非迁移潮调制而形成的四峰纵向结构的假设相一致。此外，4个极大区都有向东移动的趋势，传播速度可达10 s /s。
[1] Longitudinal structure of the equatorial ionosphere during the 24 h local time period is observed by the FORMOSAT-3/COSMIC (F3/C) satellite constellation. By binning the F3/C radio occultation observations during September and October 2006, global ionospheric total electron content (TEC) maps at a constant local time map (local time TEC map, referred as LT map) can be obtained to monitor the development and subsidence of the four-peaked longitudinal structure of the equatorial ionosphere. From LT maps, the four-peaked structure starts to develop at 0800–1000 LT and becomes most prominent at 1200–1600 LT. The longitudinal structure starts to subside after 2200–2400 LT and becomes indiscernible after 0400–0600 LT. In addition to TEC, ionospheric peak altitude also shows a four-peaked longitudinal structure with variation very similar to TEC during daytime. The four-peaked structure of the ionospheric peak altitude is indiscernible at night. With global local time maps of ionospheric TEC and peak altitude, we compare temporal variations of the longitudinal structure with variations of E × B drift from the empirical model. Our results indicate that the observations are consistent with the hypothesis that the four-peaked longitudinal structure is caused by the equatorial plasma fountain modulated by the E3 nonmigrating tide. Additionally, the four maximum regions show a tendency of moving eastward with propagation velocity of several 10 s m/s.