Revisit to Sporadic E Layer Response to Presumably Seismogenic Electrostatic Fields at Middle Latitudes by Model Simulation

Ionospheric anomalies before earthquakes termed as seismo‐ionospheric precursors have been extensively discussed due to the importance of earthquake prediction. Electric field driven mechanism is commonly used to explain seismo‐ionospheric precursors. Kim et al. (1993) first theoretically demonstrated that seismogenic electric fields could form intensified sporadic E layers in higher altitudes, which is so influential that motivates considerable statistical work on variations of foEs and h'Es before earthquakes. We attempt to establish a physical model of sporadic E layers at middle latitudes based on wind shear theory with the objective to reexamine the influence of seismogenic electric fields on sporadic E layers. The results show that zonal electric fields of several mV/m can influence the formation of higher sporadic E layers: For existing higher sporadic E layers, eastward/westward electric fields are capable of inhibiting/facilitating the existing layers accompanied by ascent/descent in altitude. For normal E region without sporadic E layers, the effect of eastward electric fields is not notable, while westward electric fields are able to form wider sporadic E layers. Taking into account their complicated response and inherently high variability, a suggestion is made about the necessity to be cautious when attributing variations of sporadic E layers to forthcoming earthquakes. A sporadic E layer model considering ionospheric and metallic ions at middle latitudes is established based on shear wind theory Response of higher sporadic E layers depends on the directions of presumably seismogenic electric fields Complicated response and inherently variability of sporadic E layers make it hard to attribute sporadic E layer variations to earthquakes