大氣層與電離層之火山爆發效應

Atmospheric and Ionospheric Effects Triggered by Volcanic Eruptions

裴令凱(Ling Kai Pei)

指導教授 ： 劉正彥

國立中央大學/地球科學學院/太空科學研究所/碩士(2012年)

摘要

火山活動在地球上的天氣與氣候以及大氣層與電離層耦合扮演重要角色。劇烈的火山噴發造成大氣層溫度異常與產生電離層電子濃度擾動。本文利用福爾摩沙衛星三號紀錄與歐洲中期天氣預報中心(ECMWF)數據中之大氣溫度垂直分佈，觀測2008年至2011年共8個火山噴發指數(Volcanic Explosivity Index，VEI) ≥ 4之大規模火山噴發大氣溫度變化。8個事件中有3個呈現對流層增溫而平流層降溫，4個事件為對流層降溫而平流層增溫，以及1個兩層皆無明顯異常現象。威力強大的火山爆發產生之大氣波動可能向上傳播，引發電離層擾動。利用福衛三號掩星觀測反演之電離層電子濃度垂直分佈，可監測火山電離層波動垂直方向之波動，進一步以頻譜分析顯示主要波長約為150公里。利用聲速在電離層之理論傳播速度，並根據波長與頻率之關係，可得其火山電離層擾動之週期約為4分鐘。

關鍵字

火山爆發 ； 大氣層 ； 電離層

並列摘要

Volcanic activity plays an important role on weather/climate and atmosphere-ionosphere coupling. Volcanic eruptions can disturb atmospheric temperature and ionospheric electron density. FOMORSAT-3/COSMIC (F3/C) observations and ECMWF data are uesd to probe atmospheric temperature changes during 8 great volcanoes of Volcanic Exlosivity Index (VEI) ≥ 4. It is found that 3 out of the 8 events yield tropospheric warming and stratospheric cooling. On the contrary, 4 out of the 8 events are tropospheric cooling and stratospheric warming. 1 out of the 8 events shows no obvious change. Results show that strong volcanic eruptions could trigger pressure waves which propagate upward eventually reach the ionosphere fluctuating on the electron density within it. The HHT (Hilbert-Huang Transform) is applied to compute spectra of perturbations in the vertical profile of the ionospheric electron density and find the wavelength being around 150km. Base on the speed-wavelength relationship, the period of the perturbations are 4 minutes.

並列關鍵字

Volcanic eruption ； Atmosphere ； Ionosphere

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