| 研究生: |
陳昱璁 Chen, Yu-Tsung |
|---|---|
| 論文名稱: |
電離層電漿洞和赤道異常電漿結構與電動效應之數值模擬 Numerical simulation on structures and electrodynamics of ionospheric plasma cave and equatorial ionization anomaly |
| 指導教授: |
林建宏
Lin, Charles |
| 學位類別: |
碩士 Master |
| 系所名稱: |
理學院 - 地球科學系 Department of Earth Sciences |
| 論文出版年: | 2014 |
| 畢業學年度: | 102 |
| 語文別: | 中文 |
| 論文頁數: | 111 |
| 中文關鍵詞: | 電離層 、電漿洞 、大氣潮汐 、赤道異常 |
| 外文關鍵詞: | ionosphere,, plasma cave, atmosphere tides, equatorial ionization anomaly |
| 相關次數: | 點閱:92 下載:4 |
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本論文進行以電離層數值模型進行電離層電漿結構以及電動效應之研究,集中探討電離層電漿洞之成因與大氣潮汐與電離層全電子含量(TEC)之非線性耦合。近期大量研究指出電離層的電漿結構與中氣層至下部熱氣層的大氣潮汐有著密切的關連性,並且在電離層赤道異常帶的下方發現了兩處山洞狀的電漿匱乏帶。本研究以美國海軍研究實驗室(NRL)所開發之三維電離層數值模型SAMI3討論在不同電場以及風場結構之下電離層電漿結構之形貌。所使用的風場包括水平風場經驗模式,以及美國國家大氣中心(NCAR)開發之高層大氣模型TIME-GCM所演算之大氣水平風場。模擬實驗成功的在模型中產生電離層電漿洞的結構,進一步了解到電漿洞的產生與中性風效應產生的輻合與輻散帶分佈有關,並且發現此風場分布的產生與南北風場的TW3分量有著密切的關聯。在潮汐結構方面,則可以獲知中性風效應對TEC的影響大於電場所造成的效應,而中性潮汐對於TEC中的潮汐變化,則會因為非線性交互作用而影響到其他TEC中的潮汐分量。此外,太陽活動會明顯增加電離層F的電動效應以及熱氣層的風場,使得耦合現象的在極大期與極小期有所不同。
This thesis studies the ionospheric plasma structure and electrodynamic using theoretical simulations. This study focus on the mechanism for the formation of ionospheric plasma caves and nonlinear coupling between atmosphere tides and ionospheric total electron content. Variations of the ionospheric electron density structures related to forcing from tides propagating upward from the lower atmosphere have been studied intensively recently. Some observational studies have shown the plasma cave structure exists under the equatorial ionization anomaly. In this study, the electron density structures of plasma caves are reproduced by means of the NRL SAMI3 model, which incorporates neutral winds from the empirical Horizontal Wind Model 2007 (HWM07) and the NCAR Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIME-GCM). We discuss the relation between different electric/wind fields and ionospheric plasma structure. The simulation results show that the equatorial plasma cave structures are mainly developed by latitudinally convergent neutral winds. The tidal-decomposition analysis further suggests that the convergent neutral wind field and the intensity of the plasma cave are highly associated with the migrating terdiurnal tidal (TW3) component of the meridional neutral wind. In the simulations of the coupling between the atmospheric thermal tides and ionospheric TECs, the influence from neutral wind effects are more significant than from the electric field in ionosphere. We also find nonlinear interaction between atmosphere tides and ionospheric parameters. The level of solar activity also leads different coupling process by the enhanced F region dynamo and photoionization.
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