Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio‐sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (meff), ion composition (H+, He+, O+), and density irregularities along the geomagnetic field line
Magnetospherically reflected, specularly reflected, and backscattered whistler mode radio‐sounder echoes observed on the IMAGE satellite: 2. Sounding of electron density, ion effective mass (meff), ion composition (H+, He+, O+), and density irregularities along the geomagnetic field line
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在 IMAGE 卫星上观察到的磁层反射、镜面反射和反向散射哨声模式无线电测深仪回波：2. 沿地磁的电子密度、离子有效质量 (meff)、离子成分（H+、He+、O+）和不规则密度的探测场线
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发表时间：
2011
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通讯作者：
D. L. Carpenter
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作者：
V. Sonwalkar;A. Reddy;D. L. Carpenter
[1]Sonwalkar等人的配套论文。2011年)提供了利用图像卫星上的无线电等离子成像仪对∼5 000公里以下高度范围进行哨声模式无线电探测的新细节。本文给出了射线路径为1)在电离层上方通过折射反向传播的回波(磁层反射回波或磁共振回波)，或(2)沿∼90公里处电离层锐利下边界的反射点返回图像(斜入射(OI)或正常入射(NI)镜面反射(SR)回波)的回波的频率-群时间延迟记录。MR和OI回声路径形成窄环，而NI回声则沿着相同的射线路径往返。此外，通过多径传播或场对齐不规则(FAI)的散射，回波被发现是离散的或在时间延迟上被加宽。我们从直接解释的方法开始，使用折射率图、光线跟踪和等离子体密度模型的组合来预测当探测仪在宽范围的哨声模式频率(通常为6 kHz到63 kHz)上操作并且卫星沿着电离层上层的地磁线B0高于或低于最大FLH的高度时检测到的回波的详细频率随时间的特性。然后我们考虑逆问题，即根据观测到的回波特性估计主流等离子体密度模型的参数。由于各种回波形式对电子密度和离子有效质量Meff高度分布的敏感性不同，我们使用同时接收的MR和SR回波的观测频率对群时间延迟(Tg−f)细节来推断等离子体扩散平衡模型的性质，包括估计从O+为主的电离层到上面的轻离子制度的重要过渡区的离子组成。我们在电子密度和离子成分测量方面的结果与图像和DMSP-F15卫星上的现场测量结果、附近电离层探空仪的底部探测结果以及IRI-2007模型的值基本一致。我们还演示了一种估计沿WM回波路径或靠近WM回波路径的FAI的尺度大小和位置的方法。
[1] A companion paper by Sonwalkar et al. (2011) provided new details of whistler mode radio sounding of the altitude range below ∼5000 km by the Radio Plasma Imager (RPI) instrument on the IMAGE satellite. That paper presented frequency-vs- group time delay records of echoes whose raypaths either 1) reversed direction through refraction at altitudes above the ionosphere where the wave frequency was approximately equal to the local lower hybrid resonance frequency flh (magnetospherically reflected or MR echoes), or 2) returned to IMAGE from reflection points along the sharp lower boundary of the ionosphere at ∼90 km (obliquely incident (OI) or normally incident (NI) specularly reflected (SR) echoes). The MR and OI echo paths were shown to form narrow loops, while the NI echo followed the same raypath down and back. Furthermore, the echoes were found to be discrete or broadened in time delay either by multipath propagation or by scattering from field aligned irregularities (FAIs). We begin with a direct interpretive approach, employing a combination of refractive index diagrams, ray tracings, and a plasma density model to predict the detailed frequency-vs-time properties of echoes detected when the sounder is operated over a wide range of whistler mode frequencies (typically 6 kHz to 63 kHz) and the satellite is either above or below the altitude of the maximum flh along the geomagnetic field line B0 in the upper ionosphere. We then consider the inverse problem, estimation of the parameters of the prevailing plasma density model from the observed echo properties. Thanks to variations in the sensitivity of the various echo forms to the altitude profiles of electron density and ion effective mass meff, we use the observed frequency-vs- group time delay (tg − f) details of simultaneously received MR and SR echoes to infer the properties of a diffusive equilibrium model of the plasma, including estimates of the ion composition in the important transition region from the O+-dominated ionosphere to the light ion regime above. Our results on electron density and ion composition measurements are in general agreement with those obtained from in situ measurements on the IMAGE and DMSP-F15 satellites, with bottomside sounding results from nearby Ionosondes, and with values obtained from the IRI-2007 model. We also demonstrate a method of estimating the scale sizes and locations of FAIs located along or near WM echo paths.