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Title: 新科GNSS與Radar面面觀,-台灣地區四維電離層模式建立與應用
The Establishment and Application of Four-Dimensional Ionospheric Model in Taiwan
Authors: 林修國
Contributors: NTOU:Department of Communications Navigation and Control Engineering
Keywords: 電離層斷層掃瞄;四維電離層模式;適應性卡爾曼濾波
Computerized Ionospheric Tomography (CIT);four-dimensional ionospheric model;adaptive kalman filter
Date: 2012
Issue Date: 2013-10-07T02:31:01Z
Abstract: 台灣地區位於電離層活動極度頻繁的區域,對電離層電子含量詳細的研究可以改善 電離層活動對GNSS 定位的影響,亦可更進一步的了解電離層活動的細節。目前用於 GNSS 的電離層模式常假設電子分佈於一層位於離地表約350km 的薄膜,但事實上電子 分佈於50km 到1000km 的高空,此薄膜假設於許多情形均無法有效的描述實際的電離 層情形。台灣地區擁有世界上數一數二的高密度地面GNSS 觀測網,利用這些地面GNSS 接收站與電離層斷層掃瞄技術,可以求得電子含量的三維分布情形,由於GNSS 觀測站 均進行二十四小時的連續觀測,因此可得到三維電子含量隨時間變化的四維模型。 本計畫預計建立台灣地區四維電離層模式,用於改善GNSS 定位精度、進行太空天 氣預測參考與了解特定事件(如磁暴、地震)與電子含量變化之關聯。規劃為三年期計畫, 第一年開發以適應性卡爾曼濾波求解電離層斷層掃瞄之理論與程式,第二年利用國土測 繪中心的e-GPS 網與IGS 的資料建立台灣地區四維電離層模式並應用於GNSS 單點定 位,第三年進行四維電離層模式的應用,了解特定事件(磁暴、地震)與電子含量的關係、 與改善精密單點定位與相對定位。
Ionospheric activity is very severe in Taiwan, more detailed study of ionosphere can improve the GNSS positioning accuracy, and it can also learn more about the details of the ionospheric structure. Most available ionospheric models are based on a single ionospheric layer. An obvious drawback of such models is that they all assume that the electrons in the ionosphere are concentrated in a thin shell with an altitude between 250 through 450 km above Earth's surface. In fact, the ionosphere covers a region approximately between 50 and 1000 km above Earth's surface. This assumption would introduce extra modeling error. Taiwan has one of the best ground-based permanent GNSS network, using the measurements of the GNSS network and computerized ionospheric tomography (CIT) technology, three-dimensional total electron content (TEC) can be obtained, since GNSS reference stations provide 24-hour continuous measurements, the four-dimensional ionospheric model of time-varying three-dimensional electron content can be obtained. This project is expected to establish four-dimensional ionospheric model in Taiwan, and use this mode to improve GPS positioning accuracy, reference for space weather forecasting and understanding the association between the specific events (such as storms, earthquakes) and the changes in TEC. Planning phase of the project for three years. The progress of first year is the development CIT theory and software by adaptive kalman filter. The progress of second year is using NLSC e-GPS system and IGS data to create four-dimensional ionospheric model in Taiwan and applied to improve the positioning accuracy of GNSS single point positioning. The progress of third year is understand the association between the specific events (such as storms, earthquakes) and the changes in TEC, and applied on GNSS precise point positioning and relative positioning.
Appears in Collections:[Department of Communications Navigation and Control Engineering] Research Reports

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