GPS/MET遮蔽觀測foF2 numerical mapping與IRI 模式之比較分析

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研究生：	郭家禎 Chia-Chen Kuo
論文名稱：	GPS/MET遮蔽觀測foF2 numerical mapping與IRI 模式之比較分析 The analysis of fof2 numerical mapping between GPS/MET and IRI model
指導教授：	蔡龍治 Lung-Chih Tsai
口試委員:
學位類別：	碩士 Master
系所名稱：	地球科學學院 - 太空科學研究所 Graduate Institute of Space Science
畢業學年度：	94
語文別：	中文
論文頁數：	96
中文關鍵詞：	遮蔽觀測之數值映射
外文關鍵詞：	GPS/MET fof2 numerical mapping
相關次數：	點閱：11 下載：0
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GPS 電波遮蔽觀測技術已被應用於研究全球性電離層電子濃度的觀測。GPS/MET 系統之低軌道衛星(LEO)接收由GPS 傳播的相位訊號，在傳播的過程中，電波經過電離層時而有所影響，在球對稱的假設下，藉由Abel 積分轉換，我們可以得到從1995年4月到1997年2月，超過40000筆的電離層垂直電子濃度分布資料。而經由這些資料所繁衍的foF2值將可用在產生數值映射(numerical mapping)上。在本文中，我們選擇座標函數為球面諧波函數(spherical surface harmonic) 之線性組合，並分成下列三大群組：(1) cos 的次數代表主要緯度趨向，沒有經度的變化。(2) 級數為1之扇形(sectorial)和等軸(tesseral)諧波並包含級數為1的經度變化。(3) 級數為2之扇形(sectorial)和等軸(tesseral)諧波並包含級數為2的經度變化。所衍生出的數值映射(numerical mapping)，將與原始IRI 映射做比較。

Radio occultation technique of the Global Positioning System(GPS) has been applied to obtain vertical profile of electron density in the Ionosphere. Global Position System/Meteorology (GPS/MET) uses a satellite in low Earth orbit(LEO) to receive the phase signals of GPS radio wave affected by ionosphere while propagating through it. By using Abel integral transform under the assumption of spherical symmetry, we caculated more than forty thousands of vertical profiles of the ionospheric electron density from April 1995 to Feb 1997. And the retrieved foF2 values have been used to produce numerical maps. In this study, we choose our coordinate functions as a particular set of the functions which are linear combinations of surface spherical harmonics and are divided into three groups according to different orders from 0 to2. And the derived numerical maps will be compared with the original IRI maps.

摘要　.......................................................................................... Ι
英文摘要　................................................................................... Ⅱ
致謝　…………………………………………………………..…..… Ⅲ
圖目錄　....................................................................................... Ⅳ
表目錄　....................................................................................... Ⅳ
第一章　序論　.............................................................................. 1
1-1　前言　................................................................................ 1
1-2　電離層結構簡介　.............................................................. 3
第二章　IRI Model　..................................................................... 6
2-1　IRI 模式發展與簡介　........................................................ 6
2-2　IRI 模式中垂直電子密度分佈模式　.................................. 7
2-3　IRI for foF2 maps　.......................................................... 12
2-4　foF2 maps　.................................................................... 13
2-4-1 日變化分析　......................................................... 14
2-4-2 當地時間之修正　.................................................. 15
2-4-3 日變化分析雜訊過濾　........................................... 16
2-4-4 正交函數集之建構　.............................................. 19
2-4-5 地理變化分析　..................................................... 21
2-4-6 地理變化分析雜訊過濾　....................................... 22
第三章　電波遮蔽觀測分析方法　............................................... 28
3-1　GPS/MET 系統與電波遮蔽觀測　................................... 28
3-2　Abel 積分轉換　.............................................................. 34
3-3　電子濃度與折射係數之關係　.......................................... 35
3-4　全電子含量反演電子濃度　.............................................. 36
3-5  GPS/MET 解析度比較　................................................. 39
3-6　GPS/MET 資料分佈情形　.............................................. 40
第四章　利用GPS/MET資料作foF2數值映射　........................ 43
4-1　球諧波分析法　................................................................ 43
4-2　最佳雜訊分離　 .............................................................. 50
第五章　GPS/MET 與 IRI 模式之foF2數值映射資料比較　...... 55
5-1　foF2 之比較　................................................................. 55
5-3　foF2 數值映射之比較　................................................... 55
第六章　結論與未來展望　.......................................................... 67
參考文獻　................................................................................... 69
附錄A　IRI 程式介紹　…………………………………………….. 72
附錄B　電離層電子密度部份之計算……………………… 78
附錄C　IRI 程式中foF2 之計算　……………………………… 82

                                

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