Observations and Simulations of Atmosphere-Ionosphere Wave Coupling

  • 周 敏揚

Student thesis: Doctoral Thesis


The Earth’s ionosphere is strongly influenced by meteorological processes originating from the lower atmosphere they can affect the ionosphere through the upward propagating atmospheric waves Atmospheric waves play a crucial role in coupling the lower and upper atmosphere they can modify and modulate the ionospheric electrodynamics driving ionospheric variability and instabilities to make considerable impacts on the performances of positioning navigation reconnaissance systems and radio communication applications Since the 1960s several studies have reported that rocket launches also contribute to the ionospheric variability In this dissertation we study the ionospheric responses to natural and anthropogenic sources using the ground-based Global Navigation Satellite Systems networks (GNSS) and Naval Research Laboratory (NRL) SAMI3/ESF (Sami 3 is Also a Model of the Ionosphere) model For natural sources two Category 5 Super Typhoon Meranti and Nepartak triggered traveling ionospheric disturbances (TIDs) are studied when they swept toward Taiwan in 2016 Super Typhoon Meranti excited evident concentric waves in GNSS total electron content (TEC) are first observed These concentric waves with various scales agree well with the internal Boussinesq dispersion relation suggesting that they are associated with the primary gravity waves instead of secondary waves Additionally Perkins-type ionospheric instabilities related to Super Typhoon Nepartak are first investigated in the equatorial ionosphere Nighttime ionospheric instabilities are triggered following the concentric gravity waves it is suggested that the electrodynamic coupling between concentric gravity waves and Perkins instability may play an important role in seeding the instability SAMI3/ESF model is further used to confirm the interconnection between concentric gravity waves and ionospheric instabilities These studies provide new evidence that typhoon-induced concentric gravity waves can directly penetrate into the ionosphere modifying the ionospheric electrodynamics to trigger instabilities and disturbances in the equatorial ionosphere region For anthropogenic sources ionospheric responses to three SpaceX rocket launches comprising JASON-3 FORMOSAT-5 and Falcon Heavy missions are investigated GNSS TEC Observations show that these rocket launches can excite gravity waves and shock acoustic waves in the lower thermosphere and ionosphere causing ionospheric perturbations The rocket-induced TIDs display nearly a monochromatic spectrum that is very different from those waves generated by deep convection We report two remarkable patterns of V-shape shock acoustic waves and concentric TIDs (CTIDs) in the ionosphere during with the JASON-3 launch The characteristics of CTIDs agree well with the gravity wave dispersion relation suggesting that the CTIDs are related to the atmospheric gravity waves The optimal wave source searching and gravity wave raytracing technique suggests that the CTIDs were originated from the mesopause region after the ignition of the second-stage rocket The FORMOSAT-5 launch-induced gigantic circular shock waves and ionospheric plasma hole are studied This is the largest rocket-induced circular shock acoustic waves on record and is due to the unique nearly vertical attitude of the rocket during orbit insertion The Falcon Heavy launch-induced short-period and long-propagating TIDs are presented These short-period TIDs are most likely associated with ducted gravity waves trapping in a thermal duct Numerical simulations suggest that thermal ducted gravity waves can trigger TIDs through the electrodynamic coupling processes These studies provide a new insight into how the human activities affect our atmosphere and space environment as these anthropogenic space weather events are expected to increase at an enormous rate in the future
Date of Award2018 Jul 6
Original languageEnglish
SupervisorCharles Lin (Supervisor)

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