赤道地區電噴流與福衛三號衛星觀測電離層閃爍現象之相關性; On the Relationship between Equatorial Electrojet and Ionospheric Scintillation measured by FORMOSAT-3/COSMIC

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/5308

Title:	赤道地區電噴流與福衛三號衛星觀測電離層閃爍現象之相關性;On the Relationship between Equatorial Electrojet and Ionospheric Scintillation measured by FORMOSAT-3/COSMIC
Authors:	蔡和展;Her-Chan Tsai
Contributors:	太空科學研究所
Keywords:	電離層閃爍;赤道電噴流;Ionospheric scintillation;EEJ
Date:	2009-06-30
Issue Date:	2009-09-22 09:49:16 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	白天電離層在赤道地區常觀測到強烈的東向電流稱為赤道電噴流(EEJ)，由於電流會影響磁場變化，學者們利用地磁觀測站量測赤道電噴流影響磁場的變化，以探討赤道電噴流的形態。本文利用國際即時地磁觀測網提供的地磁觀測資料以研究赤道電噴流影響磁場變化的現象，並與福衛三號衛星測得電離層閃爍資料做比較，因此本論文主要架構分為赤道電噴流形態研究及赤道電噴流與電離層閃爍比較兩部分。本論文主要分析2007年四個節氣當日、春分附近10日、地磁寧靜期之春季與5月23日等四種情況下赤道電噴流與電離層閃爍間相關性。在研究赤道電噴流影響磁場變化部分:發現赤道電噴流的形態存在著季節性變化，而2007年春季EEJ平均發生在09~14 LT並位在磁緯度2度與-3.15度之間，赤道電噴流感應磁場最大的強度(∆H約116 nT)。在比較赤道電噴流與電離層閃爍部分:由春分當日觀測結果我們發現兩者間強度的關係呈現正相關的情形。分析多日觀測結果發現較強的電離層閃爍現象發生在赤道電噴流的邊界，而在比較磁暴日與寧靜日的觀測中我們發現當地磁擾動較強的時候赤道電噴流方向會產生改變，且赤道電噴流區域的閃爍平均值會增強，赤道電噴流與電離層閃爍在強度變化上是同步調的。 In the day time equatorial ionosphere, there has been often observed a strong eastward current which is called Equatorial Electro-Jet (EEJ). According to the Ampere’s law, the current can induce the magnetic variations in its surroundings. Therefore scientists use magnetic observatories to measure the changes of magnetic field caused by EEJ and study the morphology of Equatorial electrojet. This thesis used the magnetic observatories’ data of International Real-time Magnetic Observatory Network to study the variations of magnetic field caused by Equatorial electrojet. Then we compared the Equatorial electrojet with ionosphere scintillations (represented by S4 values) detected by the FORMOSAT-3 satellites. The main task of this thesis consists of two parts. The first part is to study the morphology of EEJ, while the second part deals with the comparisons between EEJ and ionospheric scintillations. The main purpose of this thesis is using 2007 data sets to study the relationship between EEJ and the magnetic field variations affected by the EEJ under the following conditions: during the days of equinox and solstice; during 10 quiet days near the spring equinox; quiet times during the spring season; and on the May 23 storm day. From analyses of the magnetic field variations affected by EEJ, we found that there existed a seasonal variation in the morphology of EEJ. The seasonal (2007 spring) average location of EEJ is during 9 to 14 LT and ranges from the magnetic latitude 2o N to 3.15o S, while the maximum induced ∆H was about 116 nT. From the statistical comparison between EEJ and scintillation we have the following results: on spring equinox day positive correlation was found between their intensities; 10 days’ and seasonal averages reveal that stronger scintillations occurred near the boundary of EEJ. Moreover, from the comparison of the observations on storm day and quiet days we have the following findings: on storm day the EEJ current has changed it’s direction from that of quiet day pattern; and the average S4 is generally increased in the storm time EEJ region. Both EEJ and ionosphere scintillation change coherently when they have magnitude variations.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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