Abstract The possibility of sporadic E (Es) layer formation in the mid-latitude nighttime lower thermosphere by horizontal homogeneous and inhomogeneous (vertically changing) winds is investigated by analytical and numerical solutions of continuity equation for dominant heavy metallic ions Fe+. The study firstly showed that when ions maximal vertical convergence rate exceeds the diffusive displacement of their initial layer, then their convergence into Es type thin dense layer is possible. The ions maximal convergence rate corresponds to the minimal negative values in their vertical drift velocity divergence. Es layers are localizing either at the ion vertical drift velocity nodes or at the regions where the drift velocity and convergence rates vanish. Ions ambipolar diffusion influences their convergence processes and controls Es layer densities. The wind direction, value and vertical shear, together with geomagnetic field and vertically changing ion-neutral collision frequency, determine the maximal ion/electron convergence rate, so formation and localization of Es layer is predictable. Es layers formation is possible by diversely directed horizontal wind (even it is homogeneous) at any height between 95 and 150 km, where they are observable. By the suggested theory it is shown, for the first time, that the horizontal wind with vertically changing meridional and zonal components determined by tidal wind (or atmospheric waves), as well as those taken from the horizontal wind model (e.g., HWM14) and observed data can cause the formation of a single or double peak sporadic E. In the regions with the maximal positive divergence of the ion vertical drift velocity, their density is depleting.

中文翻译：

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由均匀和非均匀水平风形成的零星 E (Es) 层

摘要 通过对主要重金属离子 Fe+ 的连续性方程的解析解和数值解，研究了在中纬度夜间低热层中由水平均匀和不均匀（垂直变化）风形成零星 E (Es) 层的可能性。该研究首先表明，当离子最大垂直收敛速度超过其初始层的扩散位移时，它们就有可能收敛成Es型薄致密层。离子最大收敛速度对应于它们垂直漂移速度发散的最小负值。Es 层位于离子垂直漂移速度节点或漂移速度和收敛速度消失的区域。离子双极扩散影响它们的收敛过程并控制 Es 层密度。风向、风值和垂直切变，加上地磁场和垂直变化的离子-中性碰撞频率，决定了最大的离子/电子收敛速度，因此 Es 层的形成和定位是可以预测的。Es 层的形成可以通过在 95 到 150 公里之间的任何高度的不同方向的水平风（即使它是均匀的）形成，在那里它们是可观察到的。建议的理论首次表明，水平风具有由潮汐风（或大气波）确定的垂直变化的经向和纬向分量，以及来自水平风模型（例如，HWM14）和观察到的数据会导致形成单峰或双峰零星E。在离子垂直漂移速度正发散最大的区域，它们的密度正在耗尽。