First Detection of the Pekeris Internal Global Atmospheric Resonance: Evidence from the 2022 Tonga Eruption and from Global Reanalysis Data
First Detection of the Pekeris Internal Global Atmospheric Resonance: Evidence from the 2022 Tonga Eruption and from Global Reanalysis Data
复制标题
首次检测到 Pekeris 内部全球大气共振：来自 2022 年汤加火山喷发和全球再分析数据的证据
DOI：
10.1175/jas-d-22-0078.1
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发表时间：
2022
影响因子：
3.1
通讯作者：
Nakano Masuo
中科院分区：
文献类型：
--
作者：
Watanabe Shingo;Hamilton Kevin;Sakazaki Takatoshi;Nakano Masuo
我们使用观测和模型模拟来研究2022年1月汤加火山爆发后数小时内主导远场的大气脉冲。我们分析了从Himawari-8地球同步卫星上获得的辐射观测结果，发现可以检测到预期水平相速度为<$315 m s-1的兰姆波阵面和相速度为<$245 m s-1的明显阵面。相速度较慢，这与Pekeris在1937年提出的全球内部共振模式以及过去世纪的其他理想化理论研究所预期的相速度一致，但从未在大气中检测到。用一个高分辨率大气环流模式对喷发后的情况进行了模拟。火山位置上方的热异常被瞬时引入到模型场中，并将模型再积分12小时。这产生了一个模拟波脉冲，在远场，同意相当不错的兰姆波的气压观测。模型结果还表明存在较慢的脉冲，这种扰动在平流层中具有180 °相移的垂直结构，与内部共振模式的理论预测一致。这意味着，在长期观测记录的分析中看到的连续振铃兰姆波全球正常模式应该有较低频率的内部Pekeris模式对应物，我们通过分析67年每小时的全球再分析数据证实了这一预测。被捕获的兰姆波和较慢的水平相速度的内部Pekeris波可以实现为全球大气的正常模式，解决了动力气象学中一个非常长期和基本的问题。我们的结果也有更广泛的影响。2022年汤加火山爆发产生了令人惊讶的巨大海洋海啸，即使在一个偏远的海洋盆地，这是可能的，较慢的大气Pekeris模式可以发挥作用，激发显着的海洋响应。此外，在大气变化中看到的谱峰对应的Pekeris正常模式提供的功能与全球模型模拟的大气，沿着与兰姆模式在早期的研究中检测到的比较。
We used observations and model simulation to examine the atmospheric pulses that dominate the far field in the hours after the January 2022 Tonga eruption. We analyzed radiance observations taken from theHimawari-8geostationary satellite and showed that both a Lamb wave front with the expected horizontal phase speed ∼315 m s−1and a distinct front with phase speed ∼245 m s−1can be detected. The slower phase speed is consistent with that expected for the global internal resonant mode that had been proposed by Pekeris in 1937 and in other idealized theoretical studies over the past century, but which had never been detected in the atmosphere. A simulation of the eruption aftermath was performed with a high-resolution atmospheric general circulation model. A hot anomaly over the volcano location was introduced instantaneously to the model fields and the model was integrated for another 12 h. This produced a simulated wave pulse that, in the far field, agreed reasonably well with barograph observations of the Lamb wave. The model results also showed the presence of the slower pulse and that this disturbance had a vertical structure with a 180° phase shift in the stratosphere, in agreement with the theoretical prediction for the internal resonant mode. An implication is that the continuously ringing Lamb wave global normal modes that have been seen in analyses of long observational records ought to have lower-frequency internal Pekeris mode counterparts, a prediction that we confirm though analysis of 67 years of hourly global reanalysis data.Significance StatementOur demonstration that both a surface-trapped Lamb wave and a slower horizontal phase speed internal Pekeris wave can be realized as normal modes of the global atmosphere resolves a very long-standing and fundamental issue in dynamical meteorology. Our result also has broader implications. The 2022 Tonga eruption produced a surprisingly large ocean tsunami even in a remote ocean basin, and it is possible that the slower atmospheric Pekeris mode can play a role in exciting the remarkable ocean response. Also the spectral peaks seen in atmospheric variability corresponding to the Pekeris normal mode provide features for comparison with global model simulations of the atmosphere, along with the Lamb modes detected in earlier studies.