Combined Effect of Topography and Rotation on Oblique Internal Solitary Wave‐Wave Interactions

Abstract

AbstractOblique interactions between internal solitary waves (ISWs) in the ocean have been frequently recorded by satellite images, nonetheless, only a limited number of studies concentrate on these phenomena, which found that both the Earth's rotation and varying topography are important factors for the underlining wave dynamics. However, the effects of rotation at different latitudes and furthermore, their combined effects with the shoaling topography are still unclear. Thus, the aim of this paper is to investigate these combined effects on oblique ISW wave‐wave interactions. Referring to observed obliquely interacting patterns, three scenarios initiated by two ISWs posing a V shape are explored using the variable‐coefficient Kadomtsev‐Petviashvili (KP) equation under the circumstance of continuous stratification and idealized shoaling topography. In all three experiments, rotation alone disintegrates the coherent waveforms and suppresses the emergence of a Mach stem (a wave generated at the interaction zone, characterized by the maximum of four‐fold initial waves). When shoaling topography is also included, which increases the nonlinearity leading to a competition with dispersion induced by rotation, and the result is a magnification of wave amplitudes and emergence of additional trailing waves. The combined effect of these two factors modulates the birth and subsequent development of the Mach stem, alters the post‐interaction patterns and determines the emergence of a nascent KdV‐like undular bore, which plausibly explains the discrepancies between previous theoretical results (when the combined effect is not considered) and the measured horizontal surface signatures for ISW wave‐wave interactions.