The Possible Role of Turbopause on Sporadic‐E Layer Formation at Middle and Low Latitudes.

In this paper, we examine the mechanism of middle‐ and low‐latitude sporadic‐E (Es) layer formation. Observations of ionosondes and meteor radars at stations of different latitudes show that Es layer also formed at low‐altitude nonwindshear points, which is distinct from prototypical windshear theory. The theoretical modeling results show that metallic ions can effectively accumulate by the combined effect of the zonal and meridional winds in the mesosphere and the lower thermosphere region. Numerical simulation results also demonstrate that metallic ions can accumulate without wind shear at lower height (90–105 km) as a consequence of the MLT winds leading to the ion drifting downward. We suggest that the turbopause at 90–105 km plays an important role in forming low‐altitude Es layer in the middle‐ and low‐latitude regions. Plain Language Summary: Sporadic‐E layer is an enhanced ionization patch, which can reflect radio wave signals, and plays a significant role in the telecommunication and navigation system. The occurrence of Es layer is inconsecutive and influenced by many factors, such as wind, electric field, and meteor input, which makes the prediction of Es layer very difficult. In this study, we try to investigate the process of the formation of Es layer from electrodynamic theory of ionosphere. Our simulation results demonstrate that the wind shear, a classical theory for the Es layer formation at midlatitude, is not the only mechanism leading to the generation of Es layer, and turbopause at 90–105 km height can provide the concentration location for metallic ions. Key Points: Windshear Theory of sporadic‐E (Es) formation is reexaminedMeteor radar and ionosonde observations show that Es can form at nonwindshear pointsSimulation results show that Es formation can be affected by the turbopause [ABSTRACT FROM AUTHOR]