Generation of Post Sunset E Region Electron Density Stratifications at the Magnetic Equator: An Analysis Using In Situ Measurements and Theoretical Estimations

Measurements of electron density/irregularities and ion drift velocity/neutral wind were undertaken with Electron Density and Neutral Wind (ENWi) payload on‐board an RH300 flight on 6 April 2018 as part of the Sounding Rocket Experiment (SOUREX1). The presence of a clearly structured ENWi measured electron density profile is an interesting feature observed on this day. Concurrently electron density/irregularities are measured by a Langmuir probe payload which confirmed the presence of stratifications in electron density. The neutral wind measurements by ENWi also reveal a structured pattern. The hodograph analysis of the neutral wind components reveals clockwise rotation indicating downward phase propagation characteristics associated with the gravity waves. Analysis of the requisite ion convergence at the magnetic equator for occurrence of electron density stratifications using the observed electron density structures during the post sunset hours in relation to the ion convergence due to gravity wave winds is performed according to earlier theoretical simulations. This analysis reveals that conditions favoring the formation of stratification related ion convergence are present therein. Thus the present study for first time uses actual measurements of neutral winds and electron densities from same instrument to demonstrate the role of gravity wave induced winds in producing ion convergence at the magnetic equatorial region Trivandrum in the post sunset hours.

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