Articles | Volume 21, issue 4
https://doi.org/10.5194/os-21-1461-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/os-21-1461-2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Determining the depth and upwelling speed of the equatorial Ekman layer from surface drifter trajectories
Nathan Paldor
CORRESPONDING AUTHOR
Fredy & Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401 Jerusalem, Israel
Yair De-Leon
Fredy & Nadine Herrmann Institute of Earth Sciences, Hebrew University of Jerusalem, Edmond J. Safra Campus, Givat Ram, 9190401 Jerusalem, Israel
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Itamar Yacoby, Hezi Gildor, and Nathan Paldor
Ocean Sci., 21, 2805–2828, https://doi.org/10.5194/os-21-2805-2025, https://doi.org/10.5194/os-21-2805-2025, 2025
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The paper examines the applicability of known linear wave theories to numerical simulations of two, zonally invariant, fundamental problems of Physical Oceanography: Geostrophic adjustment and Ekman Adjustment. By simulating the problems with a modified version of the Massachusetts Institute of Technology General Circulation Model (MITgcm) we show that neither of the known wave theories can explain the results of the simulations in large and small meridional domains and for long and short times.
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The work develops a Lagrangian theory of the transport on the continental shelf forced by periodically rotating wind driven. A strong resonance occurs when the wind stress rotates counterclockwise at the local Coriolis frequency, manifested in a fast longshore drift. For clockwise sub-inertial wind rotation the drift is directed with the coast to its right while in all other frequencies the drift is directed with the coast to its left.
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The transition from an arbitrary initial sea surface height to a geostrophic balance in which the velocity is steady was solved last century for constant Coriolis frequency, f(y), where y is the latitude. This study extends the theory to the realistic case in which f(y) is linear with y. We find that the variation in f(y) translates the steady geostrophic state westward as low-frequency Rossby waves that are harmonic in narrow domains and trapped near the equatorward boundary in wide ones.
Itamar Yacoby, Hezi Gildor, and Nathan Paldor
Ocean Sci., 21, 2805–2828, https://doi.org/10.5194/os-21-2805-2025, https://doi.org/10.5194/os-21-2805-2025, 2025
Short summary
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The paper examines the applicability of known linear wave theories to numerical simulations of two, zonally invariant, fundamental problems of Physical Oceanography: Geostrophic adjustment and Ekman Adjustment. By simulating the problems with a modified version of the Massachusetts Institute of Technology General Circulation Model (MITgcm) we show that neither of the known wave theories can explain the results of the simulations in large and small meridional domains and for long and short times.
Nathan Paldor and Lazar Friedland
EGUsphere, https://doi.org/10.5194/egusphere-2025-5187, https://doi.org/10.5194/egusphere-2025-5187, 2025
This preprint is open for discussion and under review for Ocean Science (OS).
Short summary
Short summary
The work develops a Lagrangian theory of the transport on the continental shelf forced by periodically rotating wind driven. A strong resonance occurs when the wind stress rotates counterclockwise at the local Coriolis frequency, manifested in a fast longshore drift. For clockwise sub-inertial wind rotation the drift is directed with the coast to its right while in all other frequencies the drift is directed with the coast to its left.
Itamar Yacoby, Nathan Paldor, and Hezi Gildor
Ocean Sci., 19, 1163–1181, https://doi.org/10.5194/os-19-1163-2023, https://doi.org/10.5194/os-19-1163-2023, 2023
Short summary
Short summary
The transition from an arbitrary initial sea surface height to a geostrophic balance in which the velocity is steady was solved last century for constant Coriolis frequency, f(y), where y is the latitude. This study extends the theory to the realistic case in which f(y) is linear with y. We find that the variation in f(y) translates the steady geostrophic state westward as low-frequency Rossby waves that are harmonic in narrow domains and trapped near the equatorward boundary in wide ones.
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Short summary
The study combines archived surface drifter trajectories along the Equator with a novel extension of Ekman's wind-driven theory to the equatorial β-plane in order to estimate the depth of the equatorial Ekman layer and the speed of upwelling into it. The analysis provides a direct estimate of the depth of the equatorial Ekman layer based on observed drifter trajectories and does not involve the 3D continuity equation, which is only used for estimating the upwelling speed.
The study combines archived surface drifter trajectories along the Equator with a novel...