[A-OS18] Physical Oceanography (General)

[AOS18-P09] Numerical Modelling of Meteotsunami Waves: A Case Study for Western Coastal Region of Taiwan

*Yu-Chien Cheng¹, Chih-Chieh Young¹ (1.National Taiwan Ocean University)

Keywords:Meteotsunami waves, pressure disturbance, translation speed, local water depth, Proudman resonance, non-hydrostatic

Meteotsunami-waves (MT-waves) triggered by a small pressure disturbance in the moving weather system and amplified by Proudman resonance have caused numerous unexpected accidents in coastal regions, e.g., 4.78 m in Nagasaki Bay (Japan). In this study, first, we reviewed historical meteotsunami events as well as the types of weather systems around Taiwan. A two-dimensional hydrodynamic model was then developed to simulate the generation and propagation of meteotsunami waves. Generally, squall lines prone to occur in spring and autumn seasons are most likely to cause MT-waves, threatening Taiwan's western coastal regions. For numerical experiment, atmospheric forcing was determined based on the characteristics of typical squall lines passing through the Taiwan Strait, i.e., the pressure disturbance with a small drop of 5 hPa and a translation speed of 20 m/s. The modelled MT-waves with a maximum water level about 0.6 m mainly occur along the central part of western coast of Taiwan, attributed to the nearly resonant condition at the local water depth. Note that the observed data reveals some high-frequency oscillations in water level during meteotsunami events. Further study including the development of non-hydrostatic modeling is under way to clarify possible causes, e.g., sudden changes in pressure, wind, or others. More results will be separately reported soon.