Oceanic Microstructure Profilers for Autonomous Vehicles
Abstract
n steady, homogeneous, stratified oceans, the production of turbulent kinetic energy (TKE) comesfrom shear phenomena, both at the surface of the ocean (for example, the Stokes shear, giving rise to Langmuir circulations) as well as in the interior (for example, internal waves with strong shear undergoing Kelvin-Helmholtz instability). This production is mainly balanced by the dissipation rate of the TKE through molecular viscosity while a small portion is used to mix the fluid through the buoyancy flux. Measurements of the dissipation rate of the turbulence is therefore important to estimate the rate of mixing of the ocean. This type of measurements is also of great interest to national security, in particular in research areas related to subsurface hydrodynamics. Measurements of ocean turbulence and the dissipation rate of the TKE have been conducted forthe past 50 years, primarily using shear probes, whose output is directly proportional to the gradient of velocity. However, these probes are very sensitive to vibrations and their measurements cannot be directly corrected for the noise induced by the vibrations of the measurement platform. For the last decade or so, the development of unmanned underwater vehicles has opened the door to collecting measurements of the dissipation rate in very remote locations or denied areas, but remains limited to low-vibration vehicles. In this proposal, we will develop a novel oceanic microstructure profiler instrument package specifically designed for deployment on unmanned surface vehicles, capable of handling a significant level of platform vibration and account for thesemotions in the microstructure measurements. Our approach here is to combine traditional (fast response temperature and conductivity) probes with novel acoustic doppler velocimetry (ADV profilers) techniques to obtain dissipation rate measurements from such vehicles.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 06, 2021
- Source ID
- N000142112302
Entities
People
- Luc Lenain
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego