Collaborative Research: Modeling Internal Waves from Cradle to Grave

This project will examine the evolution of near inertial internal waves generated at the ocean surface, using a suite of nested very high resolution models. Internal gravity waves are thought to be responsible for the bulk of turbulence production, dissipation and mixing in the stratified ocean interior. The cutting-edge one-way nesting approach would represent energy cascades realistically, in terms of the scales those cascades preferentially occupy.

The goal is to examine the importance of isotropic vs. anisotropic turbulence and dissipation, which will transform the understanding of mixing. This is a necessary step to inform and improve modeling of heat and carbon storage and transport within the ocean. The project will involve high school and undergraduate interns recruited from local programs targeting under-represented minorities, focusing on gaining experience in manipulating, analyzing and visualizing large datasets.

Co-I Kunze is a Science Communication Fellow at the Seattle Pacific Science Center and PI Lelong is a mentor with MPOWIR, an NSF-sponsored program to mentor and retain early career women in the oceanographic research community.

The project addresses the fundamental question of how near-inertial internal waves are connected to diapycnal mixing by considering whether they directly produce small scale, nearly isotropic turbulence or whether they first create large-scale anisotropic turbulence that in turn creates small-scale turbulence. The energy cascade would be tracked from wind-forced near-inertial waves in the surface mixed-layer through refraction and trapping in a baroclinic anticyclone, downward radiation into the pycnocline, critical-layer amplification at the vortex base, instability producing turbulence, and the cascade to dissipation.

The coordinated set of simulations will produce a dynamically-coupled flow field consisting of mesoscale eddies, submesoscale filaments, near-inertial and higher frequency internal waves, shear-driven instabilities, and isotropic turbulent motions at sub-Ozmidov scales, allowing an oceanographically realistic energy cascade from the meso- to turbulent scales to be studied in detail. The work will test dynamical hypotheses linking disparate scales of motion that cannot be feasibly addressed in stand-alone simulations.

The project will recruit undergraduate students through REU programs designed to increase the diversity of students successfully prepared to pursue Earth and ocean sciences career pathways. The educational goals will focus on gaining experience in the manipulation, analysis and visualization of large data sets.

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.