Geomagnetic conjugate observation of therinospheric waves at midlatitudes

(1)研究了日本茂垣地区气辉成像仪观测到的夜间中尺度移动电离层扰动（MSTID）。在OI的气辉图像（630.0 nm和777.4 nm）中，该结构被识别为NW-SE带结构，以50 m/s的速度向西南移动。我们发现-1.2 mV/m的电场振荡足以再现观测到的气辉振幅。这个模拟的电场与DMSP F15卫星在我们的观测期间经过白原上空时观测到的电场相当。DMSP离子漂移数据表明，极化电场的振荡与气辉图像中的MSTID结构相关。(2)赤道f区大尺度气辉耗竭在两个半球向中低纬度延伸。观测点位于中低纬度地磁共轭点。在日本萨塔（磁纬24°N）及其地磁共轭点澳大利亚达尔文（磁纬22°S），用两台全天成像仪同时观测到等等等离子体气泡对63.0 nm气辉强度的明显损耗。这些观测结果表明，赤道电离层的等离子体消耗沿地磁力线延长。(3)首次利用两台中纬度全天气辉成像仪在两个半球的地磁共轭点同时观测到mstid。日本Sata的630nm全天成像仪检测到的mstid波前由西北向东南拉长。在澳大利亚达尔文的地磁共轭点观测到波前由西南向东北拉长的MSTIDs。从达尔文到沿地磁力线的磁共轭点的MSTID结构与Sata图像中的结构非常吻合。这一结果表明极化电场在mstid的产生中起着重要的作用。

(1)We have investigated a nighttime medium-scale traveling ionospheric disturbance(MSTID) observed by an airglow imager at Shigaraki, Japan. The structure was identified in the airglow images of OI (630.0 nm and 777.4 nm) as NW-SE band structures moving southwestward with a velocity of 50 m/s. We found that an electric field oscillation of -1.2 mV/m was sufficient to reproduce the observed airglow amplitudes. This modeled electric field was comparable to that observed by the DMSP F15 satellite as it passed over Shigaraki during our observing period. The DMSP ion drift data show that the oscillation of the polarization electric field correlated with the MSTID structure in the airglow image.(2)We found a large-scale equatorial F-region airglow depletions extending to low-midlatitudes in both hemispheres. The observational sites were located at low-midlatitude geomagnetic conjugate points. Clear depletions of 630.0-nm airglow intensity due to equaterial plasma bubbles were simultaneously observed with two all-sky imagers at Sata, Japan (magnetic latitude 24° N), and its geomagnetic conjugate point, Darwin, Australia (magnetic latitude 22° S). These observations indicate that plasma depletions in the equatorial ionosphere elongate along the geomagnetic field lines.(3)We report for the first time simultaneous observations of MSTIDs at geomagnetic conjugate points in both hemispheres, using two all-sky airglow imagers at midlatitudes. A 630-nm all-sky imager at Sata, Japan, detected MSTIDs with a wave front elongated from NW to SE. MSTIDs with a wave front elongated from SW to NE were observed at the geomagnetic conjugate point, Darwin, Australia. The MSTID structures mapped from Darwin to its magnetic conjugate points along the geomagnetic field lines coincide closely with those in the Sata images. This result suggests that polarization electric field plays an important role in the generation of MSTIDs.