颱風電離層效應

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Title:	颱風電離層效應
Authors:	蘇孟翰;Su, Meng-Han
Contributors:	太空科學與工程研究所
Keywords:	颱風;電離層;都卜勒;全球定位系統;typhoon;ionosphere;Doppler;GPS
Date:	2021-07-05
Issue Date:	2021-12-07 11:16:29 (UTC+8)
Publisher:	國立中央大學
Abstract:	利用電離層高頻都卜勒探測系統與全球定位系統地面接收機，聯合觀測2016年9月莫蘭蒂颱風引發電離層移行擾亂。以動態功率譜分析颱風電離層擾亂盛行頻率，並使用互相關分析與總功率分析找出各反射點記錄擾亂時間差，以計算擾亂傳播速度及其源頭方位，藉此探討與颱風之關聯性。結果顯示9月13日16:00 LT莫蘭蒂颱風於海面逐漸接近台灣時，電離層都卜勒頻移與全電子含量皆出現明顯10分鐘週期。詳細分析此一明顯週期發現都卜勒頻移與全電子含量擾亂分別以188 m/s與250 m/s水平速度來自於颱風源頭。兩速度之比例與其高度之比例相當，說明颱風電離層擾亂以近水平之方式由颱風眼上空電離層向外傳播。當9月14日莫蘭蒂颱風登陸後，電離層都卜勒頻移出現劇烈擾亂現象，藉由總功率峰值計算，得知有強大擾動包以155 m/s水平速度，來自颱風中心。;This study reports ionospheric disturbance induced by typhoon Meranti in 2016 observed by a HF (high frequency) CW (continuous wave) Doppler sounding system and the ground-based receiver of the global positioning system (GPS). Dynamic power spectrum is applied to analysis the characteristic frequency of ionospheric disturbance induced by typhoon. Cross-correlation analysis and total power analysis are used to calculate the time delay of ionospheric disturbance at each receiver station. Results show that when Typhoon Moranti approached Taiwan at 16:00 LT on September 13, 2016, the ionospheric Doppler frequency shift (DFS) and total electron content (TEC) fluctuates with 10 minutes period. An angle of arrival estimation is applied to analyze time delays observed by each receiving station to confirm the disturbance being the typhoons related and examine the associated propagations. The horizontal velocity observed by Doppler sounding system and ground-based receiver of the GPS is about 188 m/s at 200 km and 250 m/s at 250 km respectively. The ratio of these two velocities is equal to the height ratio, comfirmed that ionospheric disturbance induced by typhoon propagetes almost horizontally from the ionosphere above the eye of typhoon . When typhoon Meranti made landfall on September 14, the inonspheric DFS was severe disturbance. Through angle of arrival estimation know that this phenomenon is also related to typhoon Meranti, and its horizontal velocity is about 155 m/s.
Appears in Collections:	[Graduate Institute of Space Science] Department of Earth Sciences

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