Observations of the thermosphere using measurements from long-term Fabry-Perot interferometers

Thermosphere;Fabry-Perot interferometer (FPI);Airglow;Neutral winds

Fisher, Daniel J

关键词: Thermosphere;    Fabry-Perot interferometer (FPI);    Airglow;    Neutral winds;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/98114/FISHER-DISSERTATION-2017.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Since the ionosphere was discovered in the 1920s, numerous and diverse experiments have been conducted to classify this region of the upper atmosphere.Radar, satellites, rockets, ionosondes, global positioning system (GPS) receivers, and more have been used to probe and understand this region between Earth and space.However, the ionosphere is coupled to the neutral region of the atmosphere, known as the thermosphere, and only through knowledge of the state parameters of both regions can accurate predictions of ionospheric phenomena be made during both quiet conditions and geomagnetic storms.As a compounding factor, thermospheric data have been historically lacking compared to the plentiful plasma datasets. Neutral wind and temperature data are needed to understand and validate the physics of the upper atmosphere.As satellites do not provide high-resolution temporal coverage over a given region, stationary ground-based systems are needed to observe the thermosphere.The focus of this dissertation is to analyze the nighttime thermospheric winds and temperatures from data collected by Fabry-Perot interferometers (FPI) operating in Brazil, the United States, and Morocco.These instruments observe the 630.0-nm redline emission and estimate the neutral parameters from the Doppler shift and broadening of the spectra.The instruments provide a nearly-continuous, long-term nighttime dataset from deep solar minimum through solar maximum and the current decline.These data are required to improve the accuracy of empirical models that are commonly used to drive ionospheric simulations.We provide monthly averages from each site to be used as a baseline of the quiet-time thermospheric temperatures, zonal winds, and meridional winds.Using these climatologies, we analyze the daily, seasonal, solar, and geographic variations in the neutral parameters.Further, these climatologies are used to validate and improve the horizontal wind model (HWM), a widely used empirical model of atmospheric winds.Finally, we use storm-time neutral wind measurements along with equatorial plasma bubble (EPB) observations from a collocated all-sky imager (ASI) to study the activation of the disturbance dynamo.