Transformation of internal solitary waves under ice cover edge

Abstract

Internal wave-driven mixing is an important factor in the balance of heat and salt fluxes in the Polar Regions. The interaction between internal waves and ice cover in these areas of the ocean is complex and depends on both the characteristics of the ice and the characteristics of internal waves. Harsh environment in Arctic Ocean obstructs direct field observations of internal solitary waves thus, numerical modellings are an essential tool to overcome this shortcoming. The numerical three dimensional, free-surface, non-hydrostatic model for stratified flows using the Navier-Stokes equations in the Boussinesq approximation so called NH-POM was used for simulations of transformation of internal solitary waves under ice cover edge. As the result of the research it was shown, that propagation of internal solitary waves under edge of the ice cover may lead to their destabilization through overturning and breaking events. Such parameters as ice cover depth and internal waves amplitudes were responsible for the evolution and disintegration of an ISW beneath the ice cover while the boundary friction beneath the ice cover had little effect. During the interaction, maximum energy loss could reach about 60% near the ice edge. Interaction of ISWs with the ice edge significantly enhanced the turbulent dissipation and consequentially could potentially accelerated melting of the ice. It was suggested that the blocking parameter B, that is ratio of incident amplitude to the depth of the upper layer beneath the ice, controls the transfer of energy across the ice edge, that is, more energy is reflected if the ratio increases. When the ice depth decreased, the ice-ISW interaction and resultant dissipation weakened.