Collaborative Research: Convective and Shear Instability as Pathways to Turbulence in Internal Solitary Waves

This project aims to observe ocean turbulence and mixing processes associated with shoaling internal solitary waves and to understand their dynamics with massively parallel numerical simulations. An international team of US and Taiwanese researchers will make detailed observations of oceanic fine-structure along the propagation path of internal waves from a Taiwanese research vessel in the South China Sea, a region known as a natural laboratory due the presence of strong and predictable internal waves. These waves in the interior layering of the ocean are thought to play an important role in modulating mixing, transport and energy dissipation over shelf and slope regions of the ocean. Understanding these processes is important for understanding and predicting marine ecosystems. This project will obtain fine-scale, high-resolution observations of water mass properties, velocity, and estimates of turbulent mixing, during convective and shear instabilities within shoaling internal solitary waves, using a depth adjustable, 600m long real-time, towed chain with sensors for temperature, conductivity, pressure, and velocity. High-accuracy turbulence-resolving massively parallel numerical simulations will be performed to capture the detailed structure and dynamics of convective and shear instabilities within shoaling internal solitary waves. Combined analysis of observations and simulations, both with a unique wave-tracking capability, will significantly enhance understanding of the onset and evolution of convective and shear instabilities and quantify entrainment, turbulent mixing, and mass transport at the study site and elsewhere. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.