Three-dimensional simulation of shoaling internal solitary waves and their influence on particle transport in the southern Red Sea

Abstract

The shoaling process of a group of internal solitary waves (ISWs) in the southern Red Sea is simulated with a 3D, non-hydrostatic, high-resolution MIT general circulation model (MITgcm). The breaking and dissipation processes are well reproduced, in which a positive tail forms behind and locally moves the interface upward, causing the transformation of wave polarity as it moves onshore. With the step-like structure followed, the wave eventually evolve into smaller water bores. Combined with the parameters of the leading wave slope (Sw) of about 0.07 and topography slope (S) of about 0.01, the shoaling is suggested to follow a mild breaking process. The particle transport during the shoaling process is further examined quantitatively using the Connectivity modelling system (CMS). 38400 particles are released at six different vertical layers in the main shoaling domain. Most of the particles are transported up-and-down following the wave oscillation process then settle within 10-20 m around the original released depth. For the particles inside the breaking area, the oscillation process becomes more complex and intensified, and eventually a great portion of these particles settle far away from their released locations. The time-integrated transport distance, Ti, and the direct transport distance, Ts, are also analyzed. With Ti almost 20 times to Ts in vertical, continuous up-and-down movements are suggested during the shoaling process.