Wave amplification forced by an atmospheric pressure disturbance on the continental shelf

Abstract

The well-known 2022 Tonga volcanic tsunami event raised worldwide attention and the leading tsunamis induced by the atmospheric disturbance have been found to be small in deep-sea and greatly amplified over the continental slope. It prompted our thoughts what influences the amplification of the forced wave over continental slope. This study focuses on evolution of the forced wave induced by pressure disturbance moving from deep-sea basin to land, and aims to clarify the influences of topographic and barometric factors on the amplification ratio based on numerical experiments of the idealized problem. When a pressure disturbance moves faster than free water waves in deep-sea basin similar with the Tonga event, it is shown that the maximum amplification ratio appears at a slope neither too steep nor too mild. It is found that the relative slope length to the spatial scale of pressure disturbance is a good index for the amplification ratio. As the translational speed of pressure disturbance varies, the nearshore wave is greatly affected by the Froude number Fr in the deep-sea. It should be noted that a huge amplification can happen over the slope when Fr < 1 in deep-sea, and form a more dangerous hazard than Fr > 1.