Ionospheric Irregularities at Mars Probed by MARSIS Topside Sounding
Ionospheric Irregularities at Mars Probed by MARSIS Topside Sounding
复制标题
MARSIS 上部探测探测火星电离层不规则现象
DOI：
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
S. Ruhunusiri
中科院分区：
文献类型：
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作者：
Y. Harada;D. Gurnett;A. Kopf;J. Halekas;S. Ruhunusiri
火星的上层电离层包含各种各样的扰动，这些扰动由来自上方的太阳风强迫和来自下方的向上传播的大气波驱动。在这里，我们探讨了全球分布和变化的电离层不规则性在火星外基地周围的火星上分析顶侧探测数据从火星高级雷达的地下和电离层探测（MARSIS）仪器上火星快车。由于不规则结构会产生具有额外传播时间的偏离垂直回波，因此电离层回波迹线的扩散性可用作扰动反射表面的诊断工具。在非磁化区域上方观察到的漫射回波的特性表明，在冬季半球和太阳天顶角较高的地方，水平波长为数十至数百公里的电离层不规则性特别增强。鉴于中性重力波振幅对背景大气温度的已知逆相关性，MARSIS探测的电离层不规则性最有可能与大气重力波驱动的等离子体扰动有关。虽然在某些时间间隔内，在高太阳风动态压力下更经常观察到具有异常漫射回波的极端事件，但绝大多数漫射回波事件不受变化的太阳风条件的影响，这意味着太阳风强迫对电离层不规则性产生的影响有限。对电离层不规则性的远程和现场测量相结合，将为更好地了解火星电离层动态提供机会。
The upper ionosphere of Mars contains a variety of perturbations driven by solar wind forcing from above and upward propagating atmospheric waves from below. Here we explore the global distribution and variability of ionospheric irregularities around the exobase at Mars by analyzing topside sounding data from the Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) instrument on board Mars Express. As irregular structure gives rise to off‐vertical echoes with excess propagation time, the diffuseness of ionospheric echo traces can be used as a diagnostic tool for perturbed reflection surfaces. The observed properties of diffuse echoes above unmagnetized regions suggest that ionospheric irregularities with horizontal wavelengths of tens to hundreds of kilometers are particularly enhanced in the winter hemisphere and at high solar zenith angles. Given the known inverse dependence of neutral gravity wave amplitudes on the background atmospheric temperature, the ionospheric irregularities probed by MARSIS are most likely associated with plasma perturbations driven by atmospheric gravity waves. Though extreme events with unusually diffuse echoes are more frequently observed for high solar wind dynamic pressures during some time intervals, the vast majority of the diffuse echo events are unaffected by varying solar wind conditions, implying limited influence of solar wind forcing on the generation of ionospheric irregularities. Combination of remote and in situ measurements of ionospheric irregularities would offer the opportunity for a better understanding of the ionospheric dynamics at Mars.
影响因子：
5.2
作者：
A. Medvedev;Erdal Yiğit
通讯作者：
A. Medvedev;Erdal Yiğit
影响因子：
4.8
作者：
Morschhauser, A.;Lesur, V.;Grott, M.
通讯作者：
Grott, M.