Generation of mode 2 internal waves by the interaction of mode 1 waves with topography. (18th October 2019)

• Record Type: Journal Article
• Authors: Liu, Zihua; Grimshaw, Roger; Johnson, Edward
• Is Part Of: Journal of fluid mechanics. Volume 880(2019)
• Page Start: 799
• Page End: 830
• Publication Date: 2019-10-18
• Subjects: internal waves, -- solitary waves, -- topographic effects; Fluid mechanics -- Periodicals; 532.005
• DOI: 10.1017/jfm.2019.679
• Languages: English
• ISSNs: 0022-1120

Abstract

Abstract : Oceanic internal waves can be decomposed into an infinite set of modes, and the dominant internal mode 1 waves have been extensively investigated. Although mode 2 waves have been observed, they have not received comparable attention, especially the generation mechanisms. In this work, we examine the generation of mode 2 internal waves by the interaction of mode 1 waves with topography. We use a coupled linear long-wave theory with mode coupling through topography, combined with evolution using a Korteweg–de Vries model, to predict the mode 2 wave amplitude, in an ideal three-layer fluid model, in a smooth density stratification and in two realistic oceanic settings. We find that the mode 2 wave amplitude is usually much smaller than the incident mode 1 wave amplitude and is quite sensitive to the pycnocline thickness, topographic slope and background stratification.