全球閃電產生的電場對電離層之影響

The Effect of Global Lightning Electric Field on the Ionosphere

蔡易俽(Yi-shin Tasi)

指導教授 ： 葉惠卿

國立中央大學/地球科學學院/太空科學研究所/碩士(2008年)

摘要

本篇論文利用分析TRMM衛星上的LIS所測得的閃電資料與ROCSAT-1衛星上IPEI所提供之電離層電漿資料，以探討閃電所造成之電場對於電離層的影響。在此所使用資料是取自時間從2000/11/8到2001/2 /7(代表冬季)與2001/5/8到2001/8/8(代表夏季)閃電所產生電場與電離層電漿的濃度與離子速度來做比較。透過特殊的資料處理與篩選，分析由低高度(5~7km)閃電所產生的電場，我們利用電磁脈衝波模型(EMP Model)將產生電場向上推演至較高電離層高度(>90km)，並估計此電場是否能夠改變電離層內電漿濃度與運動方式。在2001/ 01/26與2001/02/02兩天之中各有一個時段LIS與IPEI的資料在時間與空間上有相關性，我們將LIS的資料代入EMP Model配合IRI所提供的電子濃度隨高度變化推演出電場傳遞至200km處的大小範圍約10-3~10-4V/m並與IPEI所得到的離子漂移速度反演成的電場比較，發現其兩者所得的電場大小在數量級上是相似的。此外，將兩個季節內的閃電現象與間熱帶輻合區(ITCZ)比較後發現有高度相關性，兩個現象皆有冬季(註：此處季節以北半球為主)向南半球移動，夏季向北半球移動的趨勢。最後，在此篇論文亦從初步統計的觀點來看南大西洋與南美洲閃電發生次數與地理位置上的相關性，發現在南美洲與南大西洋上的閃電大多好發在南大西洋磁場異常區(SAA)內。

關鍵字

閃電電場 ； 電離層 ； TRMM衛星 ； LIS ； ROCSAT-1衛星 ； IPEI

並列摘要

In this thesis, we analyze the data from TRMM LIS and the ROCSAT-1 IPEI payload to investigate the effects of the electric field created by the lightning on the ionosphere. The data are from two periods during 8 November 2000 to 7 February 2001(for northern winter)and 8 May 2001 to 8 August 2001(for northern summer). Based on LIS data, we use the Electromagnetic Pulses model (EMP model) to calculate the electric field generated by the lightning at low altitudes (5~7km), which can reach the bottom-side ionosphere (over 90 km) and discuss the connection between lightning electric fields and ionospheric plasma motions. From TRMM and ROSAT-1 observations, we found two spatially and temporally coincident events, respectively, on 26 January 2001 and 2 February 2001 for detailed analyses. Using lightning emission intensity data of the two events as the input to EMP model, we calculate the magnitude of electric fields that can be transmitted to 200km altitude. The magnitude ranges from 10-3 to 10-4 V/m, which is comparable to that of the electric fields inferred from the IPEI ion drift measurements. In this thesis, we also examine the morphological relationship between lightning occurrence region and the Intertropical Convergence Zone (ITCZ). Both regions are correlated well in the geographic locations and all tend to situate in the summer hemisphere. Moreover, we discuss the lightning occurrence in the regions of South America and South Atlantic Ocean. We find that there is a “lightning hot zone” in the South Atlantic magnetic Anomaly (SAA) region.

並列關鍵字

LIS ； TRMM satellite ； Lightning Electric Field ； ionosphere ； IPEI ； ROCSAT-1 satellite

參考文獻

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