利用中壢特高頻雷達研究中緯度電離層散塊Ｅ層公尺級不規則體之動力行為

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Title:	利用中壢特高頻雷達研究中緯度電離層散塊Ｅ層公尺級不規則體之動力行為
Authors:	林廷翰;Ting-Han Lin
Contributors:	太空科學研究所
Keywords:	重力波;場沿不規則體;特高頻雷達;雷達干涉法;中性風場;電離層散塊E層;Neutral wind;Gravity wave;Interferometry;VHF Radar;Field-aligned irregularities;Ionosphere sporadic E layer
Date:	2009-06-12
Issue Date:	2009-09-22 09:48:59 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	新中壢特高頻雷達站52MHz電離層天線陣列於2008年1月完成天線的更新，隨即於1月底至2月初收到電離層公尺級場沿不規則體的回波。本文利用2008年2月7~8日、10月5~6日、10月8~9日三段時間的散塊E層公尺級場沿不規則體回波，針對其空間變化、時間變化、回波特性變化做定性或定量的分析。其中，發現不規則體回波的平均都卜勒速度隨時間的大小變化，有類似波狀的結構，並隨高度的增加產生一時間提前，計算出其相速度約1.25m/s向下傳播，其成因可能為重力波所造成；經由雷達干涉法將不規則體的trace velocity隨時間的變化求出後，發現與不規則體回波的平均都卜勒速度隨時間變化互為反相，文中對此一現象將提出解釋；另一方面，由不規則體回波的平均都卜勒速度隨高度的變化發現，在某些時間有明顯的速度切變結構，可藉此推測回波區域的局部性中性風切變化，最後，由平均都卜勒速度垂直切變的大小和回波頻譜寬、回波強度的相關性，推測中性風場對散塊E層特性的影響。 The ionospheric antenna array of Chung-Li 52MHz VHF radar station was rebuilt in January 2008. We observed sporadic E (Es) 3-meter field-aligned irregularities (FAI) with this array after phase calibrated in February 2008. In this thesis, we estimated the spatial structures of the echo patterns and temporal variation of mean Doppler velocity of night-time Es FAI. The results show that there were wave-like modulations in the temporal variation of FAI mean Doppler velocity with a downward phase velocity of about 1.25 m/s. We also found that the temporal variation of mean Doppler velocity of FAI is roughly 180° out of phase with the temporal variation of trace velocity of FAI layer structures. From data analysis, we speculated that the FAI mean Doppler velocity vertical shear was very likely to attribute to the vertical shear of neutral wind. The relation between neutral wind shear and generation mechanism of FAI was discussed by comparing the vertical shear of mean Doppler velocity with averaged spectral width and averaged echo power.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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