EXCITATION OF ATMOSPHERIC OSCILLATIONS BY VOLCANIC-ERUPTIONS
EXCITATION OF ATMOSPHERIC OSCILLATIONS BY VOLCANIC-ERUPTIONS
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DOI：
10.1029/94jb01475
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发表时间：
1994-11-10
影响因子：
3.9
通讯作者：
HARKRIDER, DG
中科院分区：
文献类型：
--
作者：
KANAMORI, H;MORI, J;HARKRIDER, DG
我们研究了1991年皮纳图博火山和1982年埃尔奇琼火山喷发时观测到的周期约为300秒的大气振荡机制。据报道，皮纳图博火山喷发在T = 270秒和230秒处有两个明显的频谱峰值，埃尔奇琼火山喷发在T = 195秒和266秒处有两个明显的频谱峰值；我们在1980年圣海伦斯火山和1883年喀拉喀托火山喷发中也发现了类似的振荡。为了解释这些观测结果，我们研究了置于等温大气中的两种理想化源——“质量注入”源和“能量注入”源的激发问题。一般来说，“声学”和“重力”两种振荡模式可以被激发。对于实际的大气参数，声学模式和重力模式的周期分别为275秒和304秒。对于实际的火山喷发时间历程，总能量为10¹⁷焦耳的能量注入源能够激发振幅为50到100帕（0.5到1毫巴）的大气振荡。这一结果与观测结果相符，为解释火山喷发激发的大气振荡提供了物理基础。
We investigated the mechanism of atmospheric oscillations with periods of about 300 s which were observed for the 1991 Pinatubo and the 1982 El Chichon eruptions. Two distinct spectral peaks, at T = 270 and 230 s for the Pinatubo eruption and at T = 195 and 266 s for the El Chichon eruptions, have been reported; We found similar oscillations for the 1980 Mount St. Helens and the 1883 Krakatoa eruptions. To explain these observations, we investigated excitation problems for two types of idealized sources, ''mass injection'' and ''energy injection'' sources, placed in an isothermal atmosphere. In general, two modes of oscillations, ''acoustic'' and ''gravity'' modes, can be excited. For realistic atmospheric parameters, the acoustic and gravity modes have a period of 275 and 304 s, respectively. For a realistic time history of eruption, atmospheric oscillations with an amplitude of 50 to 100 Pa (0.5 to 1 mbar) can be excited by an energy injection source with a total energy of 10(17) J. This result is consistent with the observations and provides a physical basis for interpretation of atmospheric oscillations excited by volcanic eruptions.