A Numerical Investigation of Meteotsunami Shoaling Over Mild Sloping Bottoms
Abstract
Recent studies suggest that during its nonlinear shoaling transformation over a mild-sloping bottom, a meteotsunami tends to disintegrate into very short (down to ~10s) pulses, that even modern tidal gauges fail to capture. Although simplified theoretical representations of this type of process are available, in practice understanding meteotsunami nonlinear shoaling evolution is complicated by additional factors, such as refractive topography; multiple, interacting meteotsunami waves; strong bottom dissipation; the presence of energetic wind wave fields; and others. While numerical simulations could be used to address some of these questions, the numerics of meteostunami simulations is not trivial. Meteotsunamis are commonly generated and propagate in a shallow water environment, however, the steepening of the front induced by shallow-water propagation and shoaling leads to an increased role of dispersion terms, and thus a shift from non-dispersive to weakly-dispersive evolution - the opposite "order" of typical shoaling evolution of wind waves. The observations of the disintegration of a meteotsunami into solibores and single solitons are an illustration of this process. In addition, this disintegration corresponds to a cascade of energy from spatial scales in the order of kilometers to order of meters, which presents a challenge for numerical models.
The long term goal of our research is to develop numerical tools to allow for investigating meteotsunami shoaling and associated processes. Here we present a numerical investigation of nonlinear shoaling of a meteotsunami based on the FUNWAVE-TVD, a phase-resolving nearshore numerical wave model that solves fully-nonlinear Boussinesq-type wave equations, using a combined finite-volume and finite-difference method. Meteotsunami waves are represented as single, positive perturbations of free surface elevation propagating at various angles over a plane, mild-sloping beach. We investigate the behavior of the meteotsunami wave as a function of characteristic parameters such as wave height, beach slope, and angle of propagation. The model simulations are validated by comparisons, in simple cases (shore normal propagation), with analytical and numerical simulations using other well-tested models such as the variable-coefficient KdV equation.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH43F1002J
- Keywords:
-
- 4315 Monitoring;
- forecasting;
- prediction;
- NATURAL HAZARDS;
- 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDS;
- 4341 Early warning systems;
- NATURAL HAZARDS;
- 4564 Tsunamis and storm surges;
- OCEANOGRAPHY: PHYSICAL