The importance of electric field or/and neutral wind in formation and prediction of sporadic E (Es) at the equatorial and mid-latitude regions

Abstract

This study investigates the formation and localization of sporadic E(Es) at equatorial and mid-latitude regions in case of presence of electric field or/and neutral wind. It has been shown that at the equatorial region, in analogy to the mid-latitude regions, the necessary condition for development of ion vertical convergence and formation of sporadic E (Es) is the presence of the minimal negative value of ion drift velocity divergence in its height profile (including only a vertical component). This condition at the equatorial region is significantly determined by the neutral wind velocity and the zonal and vertical components of the electric field, even when this field is homogeneous. The ions vertical convergence developed in these regions and the formation of the Es layer can take place against the background of their upward or downward drift. Sporadic layer localizes either at the node of the ions drift velocity, or in the regions where this velocity disappears. The formation and dynamics of Es layers are demonstrated by numerical methods which makes possible its prediction. The effects of the zonal and vertical components of the electric field, as well as the wind velocity (determined by the HWM14 data), on the processes of ion convergence/divergence development, at equatorial and mid-latitudes, are shown. In these cases, the ion convergence/divergence, induced by the electric field, can affect both the formation and disruption (depletion) of the Es layer formed by neutral wind, and can also increase its density or/and form an additional layer. It is also shown that the presence of electric field, along with the meridional and zonal wind at mid-latitudes, can affect both the formation and the behavior of Es layers at these regions.