A study of daytime MSTIDs over equatorial and low latitude regions during tropospheric convection: observations and simulations

• Ano de defesa: 2017
• Autor(a) principal: Olusegun Folarin Jonah
• Orientador(a): Eurico Rodrigues de Paula, Esfhan Alam Kherani
• Banca de defesa: Alexandre Alvares Pimenta, Cesar Valladares, Virgínia Klausner de Oliveira
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Instituto Nacional de Pesquisas Espaciais (INPE)
• Programa de Pós-Graduação: Programa de Pós-Graduação do INPE em Geofísica Espacial/Ciências do Ambiente Solar-Terrestre
• País: BR
• Link de acesso: http://urlib.net/sid.inpe.br/mtc-m21b/2017/02.02.15.30

Medium Scale Travelling Ionospheric Disturbances (MSTIDs) are the highly dynamical phenomenona covering all latitudes in the F region ionosphere and they propagate a long distance, often in the form of wave-fronts. Their presence in a wide region pose threat to the radio propagation and trigger the equatorial plasma bubble which disrupts the GNSS navigation system. Atmospheric Gravity Wave (AGW) is believed to be the cause of these MSTIDs during daytime. However, the seeding mechanism of these AGWs is still a research question. The objective of this thesis is to study the dynamics of daytime MSTIDs over Brazil using detrended TEC, with focus on understanding their propagation characteristics. In addition, this thesis also presents novel results on daytime MSTIDs geomagnetic conjugate mapping characteristics and mechanisms responsible. Both observational and theoretical tools are employed to pursue these objectives. Observational data obtained using instruments such as a network of GNSS receivers, digisonde, low-orbiting satellites (COSMIC) and meteorological satellites (GOES Satellite) are analyzed to identify the driving source of MSTIDs-AGW. Interesting characteristics associated with the widely pursued convective-AGWs driven generation mechanism from past literatures, are investigated. This mechanism is further studied theoretically, by adapting a Convectional-Atmosphere-Ionosphere-Coupled model (CAI-CM) to incorporate the dynamics of convectively generated AGWs and their coupling to the ionosphere. The numerical simulation work also utilizes the SAMI3 (Sami3 is Another Model of the Ionosphere) model to capture the fundamental physics of the ionosphere. The SAMI3 model is used to simulate a large region of the ionosphere for the self-consistent development of MSTIDs. Finally the simulated MSTIDs from both CAI-CM and SAMI3 model are compared with the observed MSTIDs.