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Meteotsunamis Generated by Thunderstorms

Authors :
Wijeratne, E. M. S.
Pattiaratchi, Charitha B.
Source :
Journal of Geophysical Research - Oceans; August 2024, Vol. 129 Issue: 8
Publication Year :
2024

Abstract

South‐west Australia has been identified as a global hotspot for the occurrence of meteotsunamis. In this study, a numerical hydrodynamic model (Regional Ocean Modelling System) was configured to investigate the generation of meteotsunamis through propagating thunderstorms. A range of simulations were performed using realistic and synthetic atmospheric forcing to establish the sensitivity of meteotsunami wave heights and waveforms along different parts of the coast to variations in the propagation speed and bandwidths of propagating pressure jumps associated with the thunderstorms. When a pressure jump propagated from the north and north‐west quadrants with a speed (U) of 8–15 ms−1, both the Proudman and Greenspan resonances were possible mechanisms for the generation of meteotsunamis. However, the response changed for different bandwidths of the propagating pressure jump and resulted in different meteotsunami waveforms at the coast. When U> 15 ms−1, long waves were amplified initially through shoaling at the shelf slope, with Proudman resonance enhancing the wave heights at corresponding resonant depths on the shelf, and then propagated as free waves on the continental shelf. The waves were further amplified at the coast through refraction and shoaling effects and resulted in an elevation wave at the coast. Numerical simulations also indicated that edge waves can also be excited near the coast when the incoming free wave wavelengths were equal to or half the edge wave wavelength. The study provides observational and numerical evidence to suggest that the bandwidth of propagating air pressure jumps plays a major role in meteotsunami generation and their waveforms. The numerical simulation results show that meteotsunamis on the southwest Australian coast can be generated over a range of traveling pressure jump speeds and bandwidths, where Proudman resonance, Greenspan edge wave, refraction, and shoaling were responsible for the initial wave amplification. The simulations also revealed that resonance and shoaling amplification were determined by both the speed and bandwidth of the propagating pressure jumps. The pressure jump with constant translational speed can cause significantly different wave heights and waveform meteotsunami when the bandwidths were different. As the wave propagates southward with speeds of 15–28 ms−1, it undergoes subcritical, critical, and supercritical states over the shelf. The findings of this study provide preliminary guidelines for forecasting meteotsunamis generated by summer thunderstorms along the south‐west Australian coastline. A range of moving atmospheric pressure jump speeds were conducive to meteotsunami generation on the southwest Australian coastProudman resonance, Greenspan edge waves, refraction, and shoaling were responsible for the generation and amplification of meteotsunamisThe resonance and shoaling amplification were influenced by both the speed of propagation and the bandwidths of the pressure jumps A range of moving atmospheric pressure jump speeds were conducive to meteotsunami generation on the southwest Australian coast Proudman resonance, Greenspan edge waves, refraction, and shoaling were responsible for the generation and amplification of meteotsunamis The resonance and shoaling amplification were influenced by both the speed of propagation and the bandwidths of the pressure jumps

Details

Language :
English
ISSN :
21699275 and 21699291
Volume :
129
Issue :
8
Database :
Supplemental Index
Journal :
Journal of Geophysical Research - Oceans
Publication Type :
Periodical
Accession number :
ejs67246854
Full Text :
https://doi.org/10.1029/2023JC020662