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

中低纬电离层极化电场沿地磁场传播，衰减较小。因此，由于这种效应，预计e区和f区将出现紧密的电磁耦合过程。然而，它们很难被观察到。在本项目中，我们通过同时观测E区和f区电离层沿同一地磁场的不规则性，研究了电动力学耦合过程。我们于2004年6 - 8月进行了F- e区电离层耦合研究（FERIX）。位于山形坂田的低热层廓线雷达（LTPR）沿同一地磁场观测到了f区不规则，而位于山形坂田的低热层廓线雷达（MU）观测到了e区不规则。在实验期间，国立信息通信技术研究所（NICT）在包括坂田在内的东北三个地点运行了FM-CW离子探空仪。利用大气成像仪进行了观测，并利用GEONET GPS网络进行了总电子含量（T…More EC）测量。结果表明：当f区不规则活动时，场相关区出现强烈的e区不规则，并以相同的相速度向西移动；在GPS-TEC的损耗区出现了f区不规则，具有中尺度的行电离层扰动（MS-TID）模式。两个区域的极化电场可能相互共振，形成相关的波状结构。我们还比较了印度尼西亚西苏门答腊岛赤道大气雷达（EAR）低纬度不规则回波和背景电离层与NICT经向电离层探测链SEALION的行为。我们发现，当赤道扩散- f （ESF）发生时，e区不规则性被抑制。这种现象可以用ESF事件的极化电场对e区不规则性的控制来解释。从这些结果中，我们可以成功地阐明E区和f区耦合过程对理解中低纬度电离层的重要性。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