Model Simulation of Ionosphere Electron Density with Dynamic Transportation and Mechanism of Sporadic E Layers in Lower Part of Ionosphere

Abstract:

There are many physical theories responsible for explanation the generation mechanism of sporadic E (Es) plasma irregularities. In middle latitude, it’s generally believed that sporadic E layers occur in vertical ion convergent areas driven by horizontal neutral wind shear. The sporadic E layers appear characteristic of abundant metallic ion species (i.e., Fe⁺, Mg⁺, Na⁺), that lifetime are longer than molecular ions by a factor of several orders, have been demonstrated by rocket-borne mass spectrometric measurements. On the basic of the GPS Radio Occultation (RO), using the scintillations of the GPS signal-to-noise ratio and intense fluctuation of excess phase, the global and seasonal sporadic E layers occurrence rates could be retrieved. In our previous study we found there is averaged 10 kilometers shift in height between the COSMIC-retrieved sporadic E layer occurrence rate and the sporadic E occurrence rate modeled from considering the convergence/divergence of Fe⁺ vertical flux. There are many reasons that maybe result in the altitude differences, e.g., tidal wind with phase shift, electric field driven force, iron species distributions. In this research, the quantitative analyses for electric field drives Es layers translations in vertical direction are presented. The tidal wind driven sporadic E layers have been simulating by modeling several nonmetallic ions (O⁺(⁴S), O⁺(²D), O⁺(²p), N⁺, N₂⁺, O₂⁺, NO⁺) and metallic ions (Fe⁺, FeO₂⁺, FeN₂⁺, FeO⁺) with wind shear transportation. The simulation result shows the Fe⁺ particles accumulate at zonal wind shear convergent regions and form the thin sporadic E layers. With the electric field taking into account, the whole shape of sporadic E layers vertical shift 2~5 km that depending on what magnitude and direction of electric field is added.