The Interaction of Dense Gravity Currents with Internal Waves*

Shoaling and breaking internal waves along a pycnocline may lead to mixing and dilution of dense gravity currents, such as brine effluent from desalination plants in near-coastal environments. A series of laboratory experiments was performed in which a shelf-slope gravity current passes through a two-layer stratification interface. A range of interfacial conditions is examined including no approaching waves at the interface (zero Froude number), and waves of varying Froude number. The characteristics of the gravity current are varied over a range of Richardson numbers. We examine the characteristics of the interaction between the gravity current and oncoming internal waves, the mixing at the interface, and the nature of the interfacial waves produced at the interface by the penetrating gravity current over a wide range of Froude and Richardson numbers using dye-based flow visualization, Planar Laser-Induced Fluorescence (PLIF), and measurements with a profiling conductivity-temperature-density (CTD) probe.