Internal solitary wave energy transformations under ridged ice cover

Propagation of internal solitary waves (ISW) under the edge of the ice cover may lead to theirdestabilization through overturning and breaking events. Factors such as ice cover depth, ridgingintensity, and internal wave amplitudes play crucial roles in the evolution and disintegration of ISWbeneath the ice cover. In the study, a numerical investigation of the transformation of ISWpropagating from open water in the stratified sea under ridged ice cover is carried out. Anonhydrostatic numerical model, that is based on the Reynolds averaged Navier-Stokes equations inthe Boussinesq approximation for a continuously stratified fluid, was used in the investigation. Thestudy focused on an idealized scenario with a vertical distribution of potential density anomaliesdesigned to replicate the summer profile of potential density observed over the Yermak Plateau inthe Arctic Ocean. In the numerical experiments, number of ice keels were placed beneath auniform-thickness ice layer. The ice keel shape was approximated by the Versoria function. It iscarried out calculations with a different ridging intensity, that is, the ratio of the maximum height ofthe keel to the distance between the keels. In present calculations, it varies from 1/1000 formoderately ridged ice to 1/20 for heavily ridged ice, which is broadly consistent with the oceanvalues. The transformation of ISW of depression is additionally governed by the blockingparameter β for a single keel, which is the ratio of the height of the minimum thickness of the upperlayer under the ice keel to the incident wave amplitude. An important characteristic of the ISW-ridged ice interaction is the loss of kinetic and available potential energy during the ISWtransformation. Energy transformation due to mixing leads to the transition of energy to backgroundpotential energy and energy dissipation. To characterize the dependence of energy loss on keelheight and distance between keels, we introduced the parameter, which is the ratio of the sum ofsubmerged ice thickness and maximal keel penetration to the distance between keels. An energyloss was estimated based on a budget of depth-integrated pseudoenergy before and after the wavetransformation. The results revealed that the energy loss increases with a decrease in distancebetween keels or an increase in keel height. The level of energy loss is highest for β values nearzero. For values β greater than 0.8, interaction is moderate or weak, and distance between the keelsno longer affects energy loss.