Turbulence Measurements from Compliant Moorings. Part I: Motion Characterization
- Pacific Northwest National Laboratory, Richland, Washington
- National Renewable Energy Laboratory, Golden, Colorado
- Applied Physics Laboratory, University of Washington, Seattle, Washington
High-fidelity measurements of turbulence in the ocean have long been challenging to collect, in particular in the middle of the water column. In response, a measurement technique has been developed to deploy an acoustic Doppler velocimeter (ADV) to midwater locations on a compliant mooring. A variety of instrumentation platforms have been deployed as part of this work with a range of dynamic motion characteristics. The platforms discussed herein include the streamlined StableMoor buoy (SMB), the Tidal Turbulence Mooring (TTM) system based on a conventional 0.9-m spherical buoy, and a 100-lb sounding weight suspended from the stern of a research vessel. The ADV head motion is computed from inertial motion sensors integrated into an ADV, and the spectra of these signals are investigated to quantify the motion of each platform. The SMB with a single ADV head mounted on the nose provided the most stable platform for the measurement of tidal turbulence in the inertial subrange for flow speeds exceeding 1.0 m s−1. The modification of the SMB with a transverse wing configuration for multiple ADVs showed a similar frequency response to the nose configuration in the horizontal plane but with large contamination in the vertical direction as a result of platform roll. While the ADV motion on the TTM was significant in the horizontal directions, the vertical motion of this configuration was the most stable of all configurations tested. The sounding weight measurements showed the greatest motion at the ADV head but are likely to be influenced by both prop-wash and vessel motion.
- Research Organization:
- National Renewable Energy Lab. (NREL), Golden, CO (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE; USDOE Office of Energy Efficiency and Renewable Energy (EERE); USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Water Technologies Office (EE-4W)
- Grant/Contract Number:
- AC05-76RL01830; AC36-08GO28308
- OSTI ID:
- 1580188
- Alternate ID(s):
- OSTI ID: 1406695
OSTI ID: 1357194
OSTI ID: 1373673
- Report Number(s):
- NREL/JA--5000-68974; PNNL--SA-120837; PNNL-SA--120837
- Journal Information:
- Journal of Atmospheric and Oceanic Technology, Journal Name: Journal of Atmospheric and Oceanic Technology Journal Issue: 6 Vol. 34; ISSN 0739-0572
- Publisher:
- American Meteorological SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English