I-SPAR BUOY: DESIGN OF A LIGHTWEIGHT SHALLOW WATER AIR-SEA MEASUREMENT PLATFORM
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Authors
Chamberlain, Vincent D., III
Subjects
air-sea interaction
atmospheric fluxes
CLASI
eddy-covariance
I-SPAR
inner-shelf
Kalman filter
momentum flux
shallow water
SPAR buoy
temperature flux
wind stress
atmospheric fluxes
CLASI
eddy-covariance
I-SPAR
inner-shelf
Kalman filter
momentum flux
shallow water
SPAR buoy
temperature flux
wind stress
Advisors
Thornton, Edward B.
MacMahan, James H.
Date of Issue
2020-12
Date
Publisher
Monterey, CA; Naval Postgraduate School
Language
Abstract
An Inner-shelf SPAR buoy (I-SPAR) for measuring atmospheric fluxes was developed for use in 7–20 m water depth as part of the ONR Coastal Land Air Sea Interaction (CLASI) effort. The design requirements are: 1) measurements obtained above the wave boundary layer (>4 m above sea level), 2) lightweight (< 100 kg), 3) dynamically stable, 4) modular for small boat transportation and deployment, and 5) able to acquire data for two months. The designed I-SPAR buoy has a 9 and 11 m length based on water depth and weighs 92 kg. The I-SPAR has an in-line configuration to reduce asymmetric wind drag. Atmospheric fluxes are estimated using a standard eddy-covariance, moving-platform technique that requires a fast-sampling sonic anemometer and inertial motion unit (IMU) to remove buoy motions and provide measurements in a geographic coordinate frame. The technique is modified by using a data-fused, Kalman filter IMU output. The I-SPAR is built with lightweight, high-strength carbon fiber tubes that are interconnected. The I-SPAR will follow low-frequency swell, where high-frequency wind waves are filtered out with a bottom damping plate. It is also designed for a maximum static tilt of 25° and a dynamic roll of 5.6° when exposed to a 15 m/s wind using vertical fins. A collocated solar-powered battery float will provide continuous power at a 50% duty cycle and includes an iridium modem for transmitting bulk statistics, including fluxes as well as providing a safety watch circle.
Type
Thesis
Description
Series/Report No
Department
Oceanography (OC)
Organization
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NPS Report Number
Sponsors
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Distribution Statement
Approved for public release. distribution is unlimited
Rights
This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.