閃電定位系統誤差模擬與比對

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題名:	閃電定位系統誤差模擬與比對
作者:	吳鎮宇;Wu, Chen-Yu
貢獻者:	太空科學研究所
關鍵詞:	閃電;雷達干涉法;時間差法;誤差模擬;線性球面模型;lightning;interferometry;time-of-arrival;error simulation;linear sperical method
日期:	2018-07-24
上傳時間:	2018-08-31 11:34:34 (UTC+8)
出版者:	國立中央大學
摘要:	中壢特高頻雷達站在民國101年增設了一套干涉天線陣列，本實驗使用此陣列進行閃電觀測。由於閃電柱具有高電子濃度的特性，因此會反射干涉天線所發射的電磁波，回波到達干涉陣列的各個接收天線的路程差，會由於十字型的擺設而有所不同，藉此可以得到閃電柱在三維空間中的座標參數，進而得到閃電在三維空間中的結構。氣象局是用TOA(Time Of Arrival)的方法進行閃電定位，以往在用TOA方法進行演算時通常只有考慮GPS測時誤差，但實際上還有許多因素會影響誤差，本研究將眾多影響因素包含傳播速度、地球曲率、高度項，建立一個新的誤差模擬模型。本實驗之目的是將氣象局的定位資料與中壢特高頻的定位資料進行比對，希望能達到校驗氣象局的定位誤差的效果。若考慮在偵測閃電機制演算法上的差異，將定義兩系統觀測到同一筆閃電的標準放寬至閃電持續時間(0.3秒)，兩系統的距離差與誤差模擬的結果有了較合理的差距。利用新的誤差模擬模型，分析不同套閃電定位系統的定位精準度，並且分析氣象局現有站址，發現在佈站上，台灣西部與台灣東部有分佈不均之情形，經模擬後發現加入花蓮以及台東站後會有較好的定位精準度。 ;The Chung-Li VHF Radar Station set up an interferometric antenna array in the Republic of China in 2012. This paper uses this array for lightning observation. Due to the high electron concentration characteristics of the lightning channel, it reflects the electromagnetic waves emitted by the transmitter. The wave path difference of the echo arriving at each receiving antenna will be different due to the cross-shaped arrangement, so that the coordinate parameter of the lightening channel in the three-dimensional space can be obtained, and then the lightning structure in the three-dimensional space can be known. The Bureau of Meteorology uses the Time Of Arrival (TOA) method to locate lightning. In the past, when the TOA method was used to locate the location, only the GPS timing error was considered. However, there are actually many factors that affect the error. Therefore, a new model, which considers all error terms needs to be established. The purpose of this experiment is to compare the locating data of the Bureau of Meteorology with the locating data of Cung-Li VHF radar, hoping to achieve the effect of verifying the locating error of the Bureau of Meteorology. However, there is still a certain gap between the comparison results of the two systems and the simulation results. If one considers the difference in the lightning detection mechanism, the criteria for both systems observing the same lightning will be redefined and the time criteria will be relaxed to 0.3 seconds (lightning event duration). After redefining the criteria, the distance difference between the two systems has a reasonable gap with the error simulation results. Using the new error simulation model to analyze the locating accuracy of different sets of lightning location systems, and to analyze the current site of the Bureau of Meteorology, it was found that there was an uneven distribution in the western part of Taiwan and eastern Taiwan. After the simulation, it was found that adding Hualien, Taitung Station will have a better locating accuracy.
顯示於類別:	[太空科學研究所 ] 博碩士論文

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