Transformation of small-scale meteorological tsunami due to terrain complexity on the western coast of Korea

Abstract

On the 4th of May, 2008, a meteorological tsunami occurred in the Yellow Sea and abnormal waves were observed at Jukdo Island, located on the western coast of Boryeong, Korea. The event attracted the attention of many engineers and scientists because it caused extreme waves only at Jukdo Island, unlike the meteorological tsunami event in 2007, which caused abnormal extreme waves along the western coast of Korea. In general, a meteorological tsunami can be forecasted using large-scale meteorological observation data and climate modeling systems. However, a small-scale meteorological tsunami like the event that occurred in 2008, which can cause abnormal extreme waves only in specific coastal areas, should be analyzed using a high-resolution modeling system because water motions can be affected by local terrain. In this study, numerical experiments were conducted to identify the generation and amplification mechanisms of the meteorological tsunami that hit Jukdo Island in 2008. To achieve this objective, we generated virtual meteorological tsunamis using atmospheric pressure disturbances observed in 2008 and simulated the propagation and run-up of the meteorological tsunamis over real topographies by varying specific Characteristics of the local terrain. A three-dimensional hydrodynamic model, MOHID, and a Boussinesq-type wave model, FUNWAVE-TVD Version 2.0, were employed to simulate the generation and transformation of the meteorological tsunamis, respectively. The numerical models were first validated by comparing the numerical results with the available tidal records observed during the event, and then used to identify the generation and amplification mechanism of the meteorological tsunami that hit Jukdo Island. Finally, the transformation of a small-scale meteorological tsunami due to terrain complexity is discussed in detail.