Experimental study of oblique interaction of internal solitary waves under ice-covered conditions

Laboratory experiments were conducted under free-surface and ice-covered conditions in a two-layer fluid system to study the effect of sea ice on the oblique interaction of internal solitary waves (ISWs). Plan-view imaging combined with grayscale calibration was used to quantify wave properties and evolution. The results show that, under ice-covered conditions, the interaction-generated wave exhibits reduced propagation speed, enhanced amplitude decay, and a significant increase in lateral spreading. These changes are consistent with a modified effective upper-layer structure and enhanced attenuation beneath the ice cover. Comparisons with Kadomtsev–Petviashvili (KP)-based simulations reproduce the general trends. However, the conservative KP model does not include dissipative mechanisms associated with the ice-covered boundary and therefore cannot fully capture the experimentally observed amplitude attenuation. Together, the experiments and simulations suggest that the ice cover modifies ISW interaction through two linked effects: a change in effective upper-layer thickness and additional attenuation that is not represented in the conservative KP model.