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Title: Turbulence Measurements from Compliant Moorings - Part I: Motion Characterization

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 mid-water 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 sub-range for flow speeds exceeding 1:0 ms -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 amore » 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.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
  2. National Renewable Energy Lab. (NREL), Golden, CO (United States)
  3. Univ. of Washington, Seattle, WA (United States)
Publication Date:
Report Number(s):
PNNL-SA-120837; NREL/JA-5000-68974
Journal ID: ISSN 0739-0572
Grant/Contract Number:
AC05-76RL01830; AC36-08GO28308
Type:
Accepted Manuscript
Journal Name:
Journal of Atmospheric and Oceanic Technology
Additional Journal Information:
Journal Volume: 34; Journal Issue: 6; Journal ID: ISSN 0739-0572
Publisher:
American Meteorological Society
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States); National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Wind and Water Technologies Office (EE-4W)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 16 TIDAL AND WAVE POWER; buoy observations; in situ oceanic observations; instrumentation/sensors; Acoustic Doppler Velocimetry; Compliant moorings; Tidal turbulence
OSTI Identifier:
1406695
Alternate Identifier(s):
OSTI ID: 1357194; OSTI ID: 1373673

Harding, Samuel, Kilcher, Levi, and Thomson, Jim. Turbulence Measurements from Compliant Moorings - Part I: Motion Characterization. United States: N. p., Web. doi:10.1175/jtech-d-16-0189.1.
Harding, Samuel, Kilcher, Levi, & Thomson, Jim. Turbulence Measurements from Compliant Moorings - Part I: Motion Characterization. United States. doi:10.1175/jtech-d-16-0189.1.
Harding, Samuel, Kilcher, Levi, and Thomson, Jim. 2017. "Turbulence Measurements from Compliant Moorings - Part I: Motion Characterization". United States. doi:10.1175/jtech-d-16-0189.1. https://www.osti.gov/servlets/purl/1406695.
@article{osti_1406695,
title = {Turbulence Measurements from Compliant Moorings - Part I: Motion Characterization},
author = {Harding, Samuel and Kilcher, Levi and Thomson, Jim},
abstractNote = {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 mid-water 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 sub-range for flow speeds exceeding 1:0 ms-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.},
doi = {10.1175/jtech-d-16-0189.1},
journal = {Journal of Atmospheric and Oceanic Technology},
number = 6,
volume = 34,
place = {United States},
year = {2017},
month = {6}
}