Study of generating mechanism of ionospheric field-aligned irregularities and E- and F-region coupling

中低纬电离层的极化电场沿地磁场传播，衰减较小。因此，由于这一效应，预计在E区和F区将发生密切的电磁耦合过程。然而，它们很难被观察到。在这个项目中，我们通过同时观测同一地磁场上的电离层E区和F区的不规则性来研究电动力学耦合过程。1.我们于2004年6-8月进行了F区和E区电离层耦合研究。位于山形Sakata的MU雷达观测到了F区的不规则性，而位于山形的LTPR(低热层廓线雷达)观测到了沿同一地磁场的E区的不规则性。在实验期间，国家信息和通信技术研究所(NICT)在东北的三个地点操作FM-CW电离层探空仪，包括Sakata。大气成像仪观测和总电子含量(T…还利用GeoNet GPS网络进行了更多的EC)测量。结果表明，当F区不规则性活跃时，场相关区出现强烈的E区不规则性，并以相同的相速度向西移动。在GPS-TEC的衰减区出现了F区不规则性，并出现了中等尺度的电离层行进扰动(MS-TID)模式。2.我们还比较了印度尼西亚西苏门答腊岛赤道大气雷达(EAR)的低纬不规则回波和背景电离层的行为与NICT的子午线电离层的行为。我们发现，当赤道扩散F(ESF)开始时，E区的不规则性被抑制。从这些结果中，我们可以成功地阐明E区和F区耦合过程在理解中低纬电离层中的重要性。较少

Polarization electric fields in mid- and low-latitude ionosphere propagate along the geomagnetic field with small attenuation. Close electromagnetic coupling processes are thus expected in the E-region and F-region owing to this effect. They are, however, difficult to be observed. In this project we studied the electrodynamic coupling processes by means of simultaneous observations of E- and F-region ionospheric irregularities along the same geomagnetic field.1.We conducted FERIX (F- and E-Region Ionospheric Coupling Study) in June-August 2004. The MU radar in Shigaraki observed the F-region irregularities while E-region irregularities along the same geomagnetic field were observed with LTPR (Lower Thermosphere Profiler Radar) located in Sakata, Yamagata. During the experiment, National Institute of Information and Communications Technology (NICT) operated FM-CW ionosondes in three locations in Tohoku including Sakata. Observations with atmospheric imagers and total-electron content (T … More EC) measurement with the GEONET GPS network were conducted as well. The results show that, when F-region irregularities were active, intense E-region irregularities appear at the field-associated region, and they moved westward with the same phase speed. F-region irregularities appeared at the depleted region of the GPS-TEC with middle-scale traveling ionospheric disturbances (MS-TID) patterns. It is possible that polarization electric fields in both regions resonant each other to develop the associated wavelike structures.2.We also compared low-latitude irregularity echoes from the equatorial atmosphere radar (EAR) in West Sumatra, Indonesia and behavior of the background ionosphere with the meridional ionosonde chain SEALION by NICT. We found that E-region irregularities were suppressed when the equatorial Spread-F (ESF) was onset. This behavior was explained by the control of E-region irregularities by the polarization electric field from the ESF event.3.From these results, we could successfully clarify the importance of E- and F-region coupling processes in understanding the mid- and low-latitude ionosphere. Less