The formation of the mid-latitude sporadic E layers ( layers) by anatmospheric vortical perturbation excited in a horizontal shear flow(horizontal wind with a horizontal linear shear) is investigated. Athree-dimensional atmospheric vortical perturbation (atmospheric shearwaves), whose velocity vector is in the horizontal plane and has a verticalwavenumber ≠0, can provide a vertical shear of the horizontal wind.The shear waves influence the vertical transport of heavy metallic ions andtheir convergence into thin and dense horizontal layers. The proposedmechanism takes into account the dynamical influence of the shear wavevelocity in the horizontal wind on the vertical drift velocity of the ions.It also can explain the multi-layer structure of layers. The patternof the multi-layer structure depends on the value of the shear-wave verticalwavelength, the ion-neutral collision frequency and the direction of thebackground horizontal wind. The modelling of formation of sporadic E layerswith a single and a double peak is presented. Also, the importance of shearwave coupling with short-period atmospheric gravity waves (AGWs) on thevariations of sporadic E layer ion density is examined and discussed.
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