Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF Radar
Concurrent measurements by satellite tracked drifters of different hull and drogue configurations and coastal high-frequency radar reveal substantial differences in estimates of the near-surface velocity. These measurements are important for understanding and predicting material transport on the oce...
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doaj-4ac024128a994b96a52641499d5a9d902020-11-24T21:23:14ZengMDPI AGRemote Sensing2072-42922018-10-011010163310.3390/rs10101633rs10101633Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF RadarSteven L. Morey0Nicolas Wienders1Dmitry S. Dukhovskoy2Mark A. Bourassa3Center for Coastal and Marine Ecosystems, School of the Environment, Florida Agricultural and Mechanical University, Tallahassee, FL 32307, USADepartment of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USACenter for Ocean—Atmospheric Prediction Studies, Florida State University, Tallahassee, FL 32306, USADepartment of Earth, Ocean, and Atmospheric Science, Florida State University, Tallahassee, FL 32306, USAConcurrent measurements by satellite tracked drifters of different hull and drogue configurations and coastal high-frequency radar reveal substantial differences in estimates of the near-surface velocity. These measurements are important for understanding and predicting material transport on the ocean surface as well as the vertical structure of the near-surface currents. These near-surface current observations were obtained during a field experiment in the northern Gulf of Mexico intended to test a new ultra-thin drifter design. During the experiment, thirty small cylindrical drifters with 5 cm height, twenty-eight similar drifters with 10 cm hull height, and fourteen drifters with 91 cm tall drogues centered at 100 cm depth were deployed within the footprint of coastal High-Frequency (HF) radar. Comparison of collocated velocity measurements reveals systematic differences in surface velocity estimates obtained from the different measurement techniques, as well as provides information on properties of the drifter behavior and near-surface shear. Results show that the HF radar velocity estimates had magnitudes significantly lower than the 5 cm and 10 cm drifter velocity of approximately 45% and 35%, respectively. The HF radar velocity magnitudes were similar to the drogued drifter velocity. Analysis of wave directional spectra measurements reveals that surface Stokes drift accounts for much of the velocity difference between the drogued drifters and the thin surface drifters except during times of wave breaking.http://www.mdpi.com/2072-4292/10/10/1633surface drifterssurface currentsHF Radar |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Steven L. Morey Nicolas Wienders Dmitry S. Dukhovskoy Mark A. Bourassa |
spellingShingle |
Steven L. Morey Nicolas Wienders Dmitry S. Dukhovskoy Mark A. Bourassa Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF Radar Remote Sensing surface drifters surface currents HF Radar |
author_facet |
Steven L. Morey Nicolas Wienders Dmitry S. Dukhovskoy Mark A. Bourassa |
author_sort |
Steven L. Morey |
title |
Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF Radar |
title_short |
Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF Radar |
title_full |
Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF Radar |
title_fullStr |
Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF Radar |
title_full_unstemmed |
Measurement Characteristics of Near-Surface Currents from Ultra-Thin Drifters, Drogued Drifters, and HF Radar |
title_sort |
measurement characteristics of near-surface currents from ultra-thin drifters, drogued drifters, and hf radar |
publisher |
MDPI AG |
series |
Remote Sensing |
issn |
2072-4292 |
publishDate |
2018-10-01 |
description |
Concurrent measurements by satellite tracked drifters of different hull and drogue configurations and coastal high-frequency radar reveal substantial differences in estimates of the near-surface velocity. These measurements are important for understanding and predicting material transport on the ocean surface as well as the vertical structure of the near-surface currents. These near-surface current observations were obtained during a field experiment in the northern Gulf of Mexico intended to test a new ultra-thin drifter design. During the experiment, thirty small cylindrical drifters with 5 cm height, twenty-eight similar drifters with 10 cm hull height, and fourteen drifters with 91 cm tall drogues centered at 100 cm depth were deployed within the footprint of coastal High-Frequency (HF) radar. Comparison of collocated velocity measurements reveals systematic differences in surface velocity estimates obtained from the different measurement techniques, as well as provides information on properties of the drifter behavior and near-surface shear. Results show that the HF radar velocity estimates had magnitudes significantly lower than the 5 cm and 10 cm drifter velocity of approximately 45% and 35%, respectively. The HF radar velocity magnitudes were similar to the drogued drifter velocity. Analysis of wave directional spectra measurements reveals that surface Stokes drift accounts for much of the velocity difference between the drogued drifters and the thin surface drifters except during times of wave breaking. |
topic |
surface drifters surface currents HF Radar |
url |
http://www.mdpi.com/2072-4292/10/10/1633 |
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