利用30MHz雷達進行中壢地區日間場沿不規則體的研究; A study of daytime irregularities in Chung Li by using 30M HZ Radar

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Title:	利用30MHz雷達進行中壢地區日間場沿不規則體的研究;A study of daytime irregularities in Chung Li by using 30M HZ Radar
Authors:	吳俊賢;Chung-hsien Wu
Contributors:	太空科學研究所
Keywords:	雷達干涉法;日間不規則體;電離層;30MHz雷達;30MHz Radar;Radar interferometry;Daytime irregularity;Ionosphere
Date:	2008-05-30
Issue Date:	2009-09-22 09:48:41 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	2005年12月28日中壢30MHz雷達觀測資料於日間電離層發現場沿不規則體，藉由場沿不規則體特性利用國際地磁參考場模型(IGRF-2000)校正系統的初始相位偏差，於進行初始相位差校正時，發現回波相位和預測回波相位區不匹配的情況，推測可能是發射波束傾斜所造成，並發現回波相位異常變化，猜測接收系統的初始差相位亦隨時間飄移，顯示觀測當天雷達系統相當不穩定。由於發射場型正確資訊無法得知，只能利用不規則體場沿特性找出該時間正確的初始相位差，做出最合理的定位。由雷達干涉法定位結果，發現2005年12月28日不規則體出現在電離層E層及高度170公里處，並藉由雷達干涉法找出不規則體空間中的位置，算出不規則體追蹤速度 (trace velocity)，並重建不規則體三度空間電漿結構，再配合頻譜分析結合動差法算出功率、平均都卜勒速度、頻寬，對E層和170公里不規則體的特性做完整的分析。其中170公里不規則體，其頻寬、垂直運動速度及出現時間，大致上都與磁赤道地區日間所觀測到150公里的場沿不規則體相同，顯示兩者之間有相當大的相關性。 The Chung-Li 30MHz radar observed daytime field-aligned irregularity (FAI) echoes on Dec. 28, 2005. In initial phase correcting process, we find the echoing phase from interferometry do not match with the expect echoing phase, which probably results from the tilte of radar beam pattern in the experiment. The analyzed results presume that the initial phase drifts with time. The results show radar system was unstable on the experiment made on Dec. 28, 2005. Because we don’t exactly know the correct beam pattern information, we can only use the condition that radar could observed irregularity when the radar beam was almost perpendicular to the magnetic field line. Using this property, we may find the expect echoing phase, and then correct the system initial phase and find the right position of irregularity. The results from interferometry show irregularities occurred in Ionosphere E region and at an altitude of 170 km. By interferometry, we can also find the position and plasma structure of irregularity in the Ionosphere, and with the spectrum analysis using moment method to calculate the total power, mean Doppler velocity, and spectrum width, which help us to realize the properties of daytime irregularity. The observed properties of daytime irregularities at height of 170 km, including the spectrum width, vertical drift velocity and local time of occurrence are the same as those observed at the equatorial region.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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