The Martian ionopause boundary detected as steep gradients in the local electron density profiles from the Mars Advanced Radar for Subsurface and Ionospheric Sounder on Mars Express is studied individually and statistically and compared to the photoelectron boundary identified by the drop of photoelectron signature due to CO₂ and O molecules. In ~90% of the cases where we have electron energy flux data, the ionopause coincides with the photoelectron boundary. The steep density gradients form at the border of the photoelectron region and above. The ionopause is observed in a wide range of latitude, longitude, and altitude. According to remote sounding investigations, the average thickness of the ionopause is ~30 km. The average altitude is between 500 and 700 km on the dayside. The altitude of the ionopause is inversely related to the solar wind dynamic pressure. Strong crustal magnetic fields increase the altitude of the boundary and they have a slight, negative effect on the occurrence only for high values. The ionopause occurs more frequently, and its altitude is higher during southern summer. The average altitude of the ionopause and solar irradiance are correlated with each other. The effect of the extreme ultraviolet flux on the occurrence rate is less noticeable.

中文翻译：

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火星离子更年期边界：与光电子边界的重合以及对内部和外部驱动器的响应

分别和统计地研究了从Mars Express上用于地下和电离层测深仪的Mars Advanced Radar的局部电子密度分布中检测到的陡峭梯度的火星电离层边界，并将其与通过CO ₂引起的光电子签名下降而确定的光电子边界进行了比较和O分子。在约90％的情况下，我们拥有电子能通量数据，离子绝经与光电子边界重合。陡峭的密度梯度在光电子区域的边界及上方形成。在较大范围的纬度，经度和海拔高度都可以看到电离层。根据遥测调查，电离层的平均厚度约为30 km。白天的平均海拔在500到700公里之间。电离层高度与太阳风动压成反比。强大的地壳磁场会增加边界的高度，并且仅在高值时才对出现的磁场产生轻微的负面影响。电离层更频繁地发生，并且在南部夏季期间其高度更高。电离层的平均高度和太阳辐照度相互关联。极紫外通量对发生率的影响不太明显。