碩士 / 國立中央大學 / 太空科學研究所 / 106 / The tides generated from the lower atmosphere can propagate upwards, causing ionospheric perturbations. Many studies have shown evidence for several types of atmosphere-ionosphere coupling in recent years. By using GPS radio occultation (RO) signals, FORMOSAT-3/COSMIC satellites can provide global morphology of the S4 scintillation index, quantifying the distribution of GPS and satellite communications disruptions.
In this study, we show the possible relation between Sporadic-E (Es) and El-Niño Southern Oscillation (ENSO) by using the FORMOSAT-3/COSMIC S4 scintillation index, Oceanic Niño Index (ONI) and tropopause height from 2007 to 2014. The long-term variation of S4 index anomaly with 3-month running mean and solar activity de-trended in the E-region shows similar trend and periods in wavelet spectrum to ENSO and tropopause height. These results indicate that ENSO signatures can be transmitted to Es formation mechanisms, potentially through modulation of vertically propagating atmospheric tides that alter lower thermospheric wind shears.
We also analyze the local time and spatial variation of the COSMIC S4 index, and quantify the major variation modes through tidal analysis from 2007 to 2014. The seasonal variations of the S4 index are presented in this method and the tidal signatures examined, to determine their distribution and overall effect on ionospheric scintillation. The global S4 index longitudinal and local time distribution is reconstructed using the results of our tidal analysis during solar minimum year (2009) and solar maximum year (2014), to determine the significance of zonal irregularities resulting from tidal disturbances.
| Identifer | oai:union.ndltd.org:TW/106NCU05069001 |
| Date | January 2018 |
| Creators | Pei-Yun Chiu, 邱珮芸 |
| Contributors | Loren C. Chang, 張起維 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 95 |
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