The lower ionosphere disturbances observed during the chain of the meteotsunamis in the Mediterranean Sea in June 2014
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The lower ionosphere disturbances observed during the chain of the meteotsunamis in the Mediterranean Sea in June 2014 M. Solovieva1 · A. Rozhnoi1 · S. Shalimov1,2 · G. Shevchenko3 · P. F. Biagi4,5 · V. Fedun6 Received: 18 January 2020 / Accepted: 3 August 2020 © Springer Nature B.V. 2020
Abstract In June 2014, a number of meteotsunamis were detected in the Mediterranean and Black Sea area. These meteotsunamis were initiated by a unique high-altitude dynamical system which was initially originated above Spain and traveled across the Mediterranean Sea towards Black Sea and Turkey. Meteotsunamis unlike tsunamis driven by strong earthquakes are local events, and their formation has different mechanism. Atmospheric internal gravity waves (IGWs) are one of the main known sources of meteotsunamis (e.g. Vilibić et al. in Pure Appl Geophys 165:2169–2195, 2008). The synoptic system produced shortlived and small-scale atmospheric pressure perturbations which drifted with the jet streamlike bubbles and generated tsunami-like waves in the open waters. The bubbles with typical dimensions 15–60 km continuously form and collapse in the atmosphere at altitudes of 3–6 km. Such a “boiled” atmosphere generated IGWs propagating both downward, where they produced meteotsunamis (presumably under Proudman resonance condition) and upward into the ionosphere, with following dissipation and excitation of plasma density perturbations. One of the few experimental techniques, which can monitor perturbations of the ionization within the lower ionosphere, uses long-wave probing by very low and low frequency (VLF/LF) radio signals. To study the ionospheric disturbances observed during the chain of meteotsunamis affecting the Mediterranean Sea, we used VLF/LF data collected in South Europe by “The International Network for Frontier Research on Earthquake Precursors”. By applying the spectral analysis method to the anomalous VLF/LF signals, it was found that revealed periods of the signal variations were from 10 to 40–70 min in different stations, which are in the range of the atmospheric pressure oscillations and the meteotsunami events. These periods also correspond to the periods of IGWs. Keywords Meteotsunami · Lower ionospheric disturbances · Radio wave propagation
* M. Solovieva [email protected] Extended author information available on the last page of the article
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Natural Hazards
1 Introduction Existence of tsunamis caused by atmospheric conditions is well known for a long time. The term “meteotsunami” became popular after works by Rabinovich and Monserrat (1996), Rabinovich and Monserrat (1998), Monserrat et al. (2006). Meteotsunamis have been observed at many locations around the world: in oceans, seas and even lakes (e.g. Šepić and Rabinovich 2014; Rabinovich and Šepić 2016). Such long waves are similar to ordinary tsunami waves and can affect coasts with the same force, although their catastrophic effects normally observed only in limited areas (in specific bays and inlets). In many places where meteotsunamis
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