Internal waves are responsible for the bulk of the diffusive mixing in the deep ocean, with implications for the rate of downward penetration of heat and carbon dioxide, as well as for the structure of the meridional overturning circulation. And yet global ocean models are far from being able to simulate the full internal wave spectrum. A new observational program, SQUID (Sampling QUantitative Internal-wave Distributions), aims to improve the broad-scale characterization of internal wave climates through global deployments of autonomous profiling floats measuring shear, strain, and turbulent mixing (using a burst-sampling approach to separate internal waves from low-frequency motions). At the same time, SQUID is compiling and sharing past datasets from velocity profiling floats and, along with other teams in the new NOPP Global Internal Waves initiative, working to transition observational results into model validation metrics and subgrid-scale mixing parameterizations.

• Deploy 50 velocity and microstructure profiling floats (ElectroMagnetic Autonomous Profiling EXplorers; EM-APEX) globally over 3 years spanning the range of the dominant parameters that determine the internal wave environment.
• Assemble past EM-APEX datasets into archived and shared resource for internal wave research.
• Derive internal wave products from profiling float mixing & energy budgets, and for data assimilation models.
• Develop operational data pathways from velocity and microstructure profile collection to operational modeling and archiving centers.
• Use the merged and augmented profiling float measurement database to assess the relative roles of sources in generating and dissipating internal waves.

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A Global Experiment to Characterize Oceanic Internal Wave Climates,
presented by James Girton at the colloquium, Theoretical and Practical Perspectives on Geophysical Fluid Dynamics, at the International Centre for Theoretical Sciences, Bengaluru INDIA