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姓名 劉忠青(Jong-Ching Liu) 查詢紙本館藏 畢業系所 太空科學研究所 論文名稱 GPS電波掩星法反演電離層散塊E層之模擬 相關論文 檔案 [Endnote RIS 格式]
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摘要(中) 由GPS電波掩星技術(Radio Occultation)可以反演出訊號強度隨高度剖面資料,而從這些訊號強度資料中可以判別散塊E層的存在與否。在這篇論文中將利用路徑尋覓法,以IRI(International Reference Ionosphere)模式為電離層背景電子濃度,模擬訊號在散塊E層中行進的情況而得到訊號強度隨高度剖面資料。在本研究中會展示若是一個無傾斜(與訊號平行)、均勻的散塊E層,會因為GPS訊號散焦(defocusing)的狀況,加上當訊號重疊時相位的疊加,在訊號強度圖中也可以看出一個U型形狀,可以由此訊號強度隨高度變化圖U型結構中的凹槽判斷此散塊E層的厚度。當把此均勻散塊E層傾斜一個角度,其U型結構會慢慢在訊號強度圖之中消失;亦或當把此散塊E層的水平延展降低至一定的長度,U型結構也會慢慢消失,這兩者皆可說明散塊E層具有遮蔽訊號的能力。而在本論文中也會將以隨機亂數產生器調整散塊E層的散亂程度,觀察其對應的訊號強度圖,以及將前面模擬結果的訊號強度圖與福衛三號(COSMIC)2008年的掩星資料做為比較。 摘要(英) he amplitude profile of GPS signal can be calculated by GPS Radio Occultation(RO), and the existence of sporadic-E can be distinguished by the profile. In this thesis, the amplitude profile of GPS signal would be simulated by ray tracing method, and the electron density information as given by IRI model. In the study, it has been shown that U-shape in amplitude profile due to the GPS signal is defocusing considering phasor
when the uniform sporadic-E is parallel with the propagation signal, and the thickness of the sporadic-E could be calculated by trough in the U-shape. When sporadic-E is tilted with the GPS signal direction, the U-shape structure was disappearing with the increase of the tilt angle; when the horizontal extension of sporadic-E is reduce, the U-shape structure was disappearing with the decrease of the horizontal extension, too. Both result can be explained that the sporadic-E is a shelter. The varied amplitude profile was simulated by the sporadic-E including the irregularity produced from different random number generator. All the amplitude profile results were compared with the COSMIC RO data in 2007.
關鍵字(中) ★ 訊號強度
★ 散塊E層
★ 模擬
★ 電波掩星
★ 厚度關鍵字(英) ★ model
★ sporadic E
★ simulation
★ radio occultation
★ thickness
★ Ray Tracing論文目次 目錄
摘要 i
Abstract ii
目錄 iv
表目錄 ix
第一章 前言 1
第二章 理論基礎 3
2.1 電離層簡介 3
2.1.1 電離層簡史 3
2.1.2 電離層定義 5
2.1.3 查普曼理論 7
2.1.4 查普曼應用 11
2.2 電離層分層 15
2.2.1 D層 15
2.2.2 E層 16
2.2.3 F層 17
2.3 電離層散塊E層與風切理論 20
2.4 折射指數與電子濃度關係 22
第三章 觀測系統與模式簡介 24
3.1 全球定位系統(Global Positioning System) 24
3.2 GPS訊號結構 26
3.3 福爾摩沙衛星三號系統 28
3.4 國際電離層參考模式(IRI model) 32
第四章 模擬過程與參數 33
4.1 光程函數與路徑覓跡法 33
4.2 模擬背景及散塊E層電子濃度 40
4.3模擬參數與模擬訊號路徑過程 43
第五章 模擬結果與討論 50
5.1 均勻層狀散塊E層 50
5.1.1 水平均勻層狀散塊E層 50
5.1.2 傾斜均勻層狀散塊E層 62
5.2 不均勻層狀散塊E層 72
5.3 模擬結果與實際COSMIC資料比較 84
第六章 結論與未來展望 87
6.1 結論 87
6.2 未來展望 89
參考文獻 90參考文獻 ﹝1﹞Appleton, E. V., “Two Anomalies in the Ionosphere”, Nature, 157, pp. 691, 1946.
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﹝3﹞Davies, K., Ionospheric radio propagation, National Bureau of Standards Monograph 80, 1965.
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﹝6﹞Hocke K, K. Igarashi, M. Nakamura, P. Wilkinson, J. Wu, A. Pavelyev, and J.Wickert, “Global sounding of sporadic E layers by the GPS/MET radio occultation experiment”, J. Atmos. Terr. Phys., Vol. 63, pp. 1973-1980, 2001.
﹝7﹞Kelly, M. C., The Earth’s Ionosphere, Plasma physics and electrodynamics, Second Edition, Academic Press. Inc., USA, 2009.
﹝8﹞Rishbeth, H. and O. K. Garriott (1969), Introduction to Ionospheric Physics, Academic Press, New York and London.
﹝9﹞Wu, D. L.,C.O. Ao, G. A. Hajj, Manuel da la Torre Juarez, and A. J. Mannucci,“Sporadic E morphology from GPS-CHAMP radio occultation”, J. Geophys. Res., Vol. 110, doi:10.1029/2004JA010701, 2005.
﹝10﹞Yeh, W. H., C. H. Huang, T. Y. Hsiao, T. C. Chiu, C. H.
Lin, and Y. A. Liou,“Amplitude morphology of GPS radio
occultation data for sporadic - E layers”, J.Geophys.
Res., Vol. 117, doi:10.1029/2012JA017875, 2012.
﹝11﹞Zeng, Z. and S. Sokolovskiy, “Effect of sporadic E clouds
on GPS radio occultation signals”, Geophys. Res. Lett.,
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﹝12﹞Zou, X., F. Vandenberghe, B. Wang, M. E. Gorbunov, Y.-H.
Kuo, S.Sokolovskiy, J. C. Chang, J. G. Sela, and R. A.
Anthes, “A ray-tracing operator and its adjoint for the
use of GPS/MET refraction angle mearsurements”, J.
Geophys. Res., 1999.
﹝13﹞安守中,全球衛星定位系統入門,全華科技圖書,2002。
﹝14﹞吳剛宏,「福衛三號電子濃度分析:電離層E 層」,國立中央大學太
空科學研究所,碩士論文,2008。
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指導教授 朱延祥(Yen-Hsyang Chu) 審核日期 2015-1-25 推文 plurk
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