Abstract. Measurements of height dependent electric field (E) and neutral wind (u) are important governing parameters of the Earth's upper atmosphere, which can be used to study e.g., how auroral currents close, or how energy flows between the ionized and neutral constituents. The new EISCAT 3D (E3D) incoherent scatter radar will be able to measure a three-dimensional ion velocity vector (v) at each measurement point, which will allow less stringent prior assumptions about E and u to be made when estimating them from radar measurements. This study investigates the feasibility of estimating the three-dimensional electric field and neutral wind vectors along a magnetic field-aligned altitude profile from E3D measurements, using the ion momentum equation and Maxwell's equations. The uncertainty of ion drift measurements is estimated for a time and height resolution of 5 s and 2 km. With the most favourable ionospheric conditions, the ion wind at E region peak can be measured with an accuracy of less than 1 m/s. In the worst case, during a geomagnetically quiet night, the uncertainty increases by a factor of around ten. The uncertainty of neutral wind and electric field estimates is found to be strongly dependent on the prior constraints imposed on them. In the lower E region, neutral wind estimates have a lower standard deviation than 10 m/s in the most favourable conditions. In such conditions, also the F region electric field can be estimated with uncertainty of about 1 mV/m. Simulated measurements of v are used to demonstrate the ability to resolve the field-aligned profile of E and u. However, they can only be determined well at the heights where they significantly influence the ion drift, that is above 125 km for E and below 115 km for u. At the other heights, the results are strongly dependent on the the prior assumptions of smoothness.

中文翻译：

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使用 EISCAT 3D 观察电场和中性风

摘要。高度相关电场 ( E ) 和中性风 ( u ) 的测量值是地球高层大气的重要控制参数，可用于研究极光电流如何关闭，或能量如何在电离成分和中性成分之间流动。新的 EISCAT 3D (E3D) 非相干散射雷达将能够在每个测量点测量三维离子速度矢量 ( v )，这将允许对E和u 的先验假设不那么严格在从雷达测量中估计它们时进行。本研究使用离子动量方程和麦克斯韦方程，研究了从 E3D 测量值沿磁场对齐的高度剖面估计三维电场和中性风矢量的可行性。离子漂移测量的不确定性估计为 5 秒和 2 公里的时间和高度分辨率。在最有利的电离层条件下，E 区峰值处的离子风可以以小于 1 m/s 的精度进行测量。在最坏的情况下，在地磁安静的夜晚，不确定性增加了大约十倍。发现中性风和电场估计的不确定性在很大程度上取决于强加于它们的先验约束。在低 E 区，在最有利的条件下，中性风估计的标准偏差低于 10 m/s。在这种情况下，F 区电场也可以以大约 1 mV/m 的不确定性进行估计。模拟测量v用于证明解析E和u的场对齐轮廓的能力。然而，它们只能在对离子漂移有显着影响的高度上才能很好地确定，即E高于 125 公里，而u低于 115 公里。在其他高度，结果强烈依赖于平滑度的先验假设。