日出電離層層峰高度和濃度對季節與太陽活動之響應

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Title:	日出電離層層峰高度和濃度對季節與太陽活動之響應
Authors:	李柏翰;Lee, Po-Han
Contributors:	太空科學與工程研究所
Keywords:	電離層;日出;層峰高度;層峰濃度;Ionosphere;Sunrise;hmF2;NmF2
Date:	2021-07-09
Issue Date:	2021-12-07 11:16:54 (UTC+8)
Publisher:	國立中央大學
Abstract:	利用福爾摩沙衛星三號11年長期觀測，研究日出期間電離層F2層層峰電子濃度結構與動力。福衛三號接收全球定位系統衛星(global positioning system, GPS)所發射之電波訊號，進行進行電離層掩星觀測，反演觀察100公里高至衛星軌道高度間電子濃度廓線資料。福衛三號自2006年4月以來累積全球超過400萬筆觀測數據，是為研究電離層天氣變化的重要資料庫。利用此一資料庫詳細研究日出期間電離層最大電子濃度(NmF2)及其高度(hmF2)在日出前後的結構與變化，探討其中之季變化、經度變化及太陽活動變化之探討。研究結果顯示日出期間電離層之hmF2及NmF2在高太陽活動時期皆高於低太陽活動時期，且具有明顯的季節變化：春、秋兩季hmF2及NmF2沿磁赤道呈現南北半球十分對稱；hmF2及日出前之NmF2以夏半球較高，日出後之NmF2則於冬半球較高。此外，磁緯度±20°N且磁偏角向東偏轉的區域在日出前1~2.5小時hmF2抬升20-30公里，推測可能和磁偏角與中性風之共軛效應有關。;Long-term radio occultation (RO) observations sounded by of FORMOSAT-3/COSMIC provide an excellent opportunity to investigate plasma structures and dynamics of the ionospheric F2-layer during the sunrise period. In total, there are more than 4,000,000 RO electron density profiles from April 2006 to December 2017. The seasonal, longitudinal, and solar activity variations of, the F2-peak height, hmF2, and electron density, NmF2, are examined during the sunrise period. Results show the hmF2 and NmF2 are higher during the high solar activity period than in the lower one. Both hmF2 and NmF2 yield hemispheric symmetry in Spring and Autumn equinox. On the other hand, 1-2.5 hours before the local sunrise, which is termed pre-sunrise ascension, the hmF2 ascends 20-30 km especially at mid-latitudes at about ±20°N in the winter hemisphere during the high solar activity period. The F2-layer starts ascending 30 minutes earlier than the usual in equinox, and becomes unclear in local summer. Meanwhile, the F2-layer ascending becomes not obvious when magnetic declination is negative or the earth’s magnetic field deflects westward. The F2-layer uplift followed by a sudden descend is attribute to the downward movement of the ionization peak during sunrise, which might result in the conjugate effect or the neutral wind effect.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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