Breakdown of Near-Surface Sea Current from High-Frequency Radar Data

To assess the contribution of wind drag and Stokes drift on the near-surface circulation, a methodology to isolate the geostrophic surface current from high-frequency radar data is developed. The methodology performs a joint analysis utilizing wind field and in situ surface currents along with an un...

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Bibliographic Details
Published in:Journal of atmospheric and oceanic technology 2022-12, Vol.39 (12), p.1927-1942
Main Authors: Cáceres-Euse, Alejandro, Molcard, Anne, Bourg, Natacha, Dumas, Dylan, Guérin, Charles-Antoine, Besio, Giovanni
Format: Article
Language:English
Subjects:
Altimeters
Coastal currents
Coastal zone
Coastal zones
Drift
Methodology
Methods
Neural networks
Ocean currents
Ocean, Atmosphere
Radar
Radar data
Radar equipment
Satellite altimetry
Satellites
Sciences of the Universe
Sea currents
Stokes drift
Surface circulation
Surface currents
Wind
Wind direction
Wind effects
Wind speed
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Summary:To assess the contribution of wind drag and Stokes drift on the near-surface circulation, a methodology to isolate the geostrophic surface current from high-frequency radar data is developed. The methodology performs a joint analysis utilizing wind field and in situ surface currents along with an unsupervised neuronal network. The isolation method seems robust in the light of comparisons with satellite altimeter data, presenting a similar time variability and providing more spatial detail of the currents in the coastal region. Results show that the wind-induced current is around 2.1% the wind speed and deflected from the wind direction in the range [18°, 23°], whereas classical literature suggests higher values. The wave-induced currents can represent more than 13% of the ageostrophic current component as function of the wind speed, suggesting that the Stokes drift needs to be analyzed as an independent term when studying surface sea currents in the coastal zones. The methodology and results presented here could be extended worldwide, as complementary information to improve satellite-derived surface currents in the coastal regions by including the local physical processes recorded by high-frequency radar systems. The assessment of the wave and wind-induced currents have important applications on Lagrangian transport studies.
ISSN:0739-0572
1520-0426
DOI:10.1175/JTECH-D-22-0013.1