A Study of the Ionosphere During the Onset of Spread F in Kwajalein PDF Download

Author: Siddhant Sudesh Rao
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Languages : en
Pages : 0

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Book Description
A study of plasma instabilities in the F-region of the equatorial ionosphere termed equatorial spread F (ESF) is undertaken considering data from recent experiments. ALTAIR radar scans from WINDY (2017) and Too WINDY (2019) and sounding rocket data from Too WINDY are analysed in an attempt to identify characteristic ionospheric conditions during the onset of ESF. A review of recent research and relevant linear plasma theory is followed by a study of experimental data. ALTAIR scans collected during WINDY are studied to identify electron density signatures that may serve as indicative signs of instability. A quantitative analysis of the same radar data led to the discovery of a characteristic spectral distribution in the small to medium scale irregularities present during the onset of ESF activity. This distribution was studied during quiet and active nights to compare the structuring of the ionosphere when stable and unstable. ESF in the moderate solar flux conditions during WINDY followed a familiar pattern beginning with small scale instability in the lower altitude bottom side and evolving into large scale instabilities in the top side of the F-region. Observations of ESF proved more elusive during Too WINDY owing to the low solar flux conditions in June of 2019. Post-sunset ESF was observed on a singular night, a much lower rate of occurrence than that during WINDY. ALTAIR data from the night of the rocket launch of Too WINDY showed the presence of post-midnight ESF over Kwajalein. Sounding rocket data confirmed the electron density measurements and revealed the presence of whistler mode hiss and ELF waves in the F-region plasma. The Cornell ionospheric simulation was used to try and reproduce the observations of post-sunset ESF from WINDY by seeding with pink noised produced using characteristics derived from the spectral analysis. Gravity waves and meridional winds were used to seed the simulation attempting to reproduce the observations of post-midnight ESF from Too WINDY but these methods showed limited success. The relevance of these experiments is finally discussed in light of other research in the field.