Title
Submesoscale tidal eddies in the wake of coral islands and reefs: Satellite data and numerical modelling
Author
Delandmeter, Philippe (Université Catholique de Louvain)
Lambrechts, Jonathan (Université Catholique de Louvain)
Marmorino, George O. (Naval Research Laboratory)
Legat, Vincent (Université Catholique de Louvain)
Wolanski, Eric (James Cook University)
Remacle, Jean-François (Université Catholique de Louvain)
Chen, Wei (Naval Research Laboratory)
Deleersnijder, E.L.C. (TU Delft Mathematical Physics; Université Catholique de Louvain) 
Date
2017
Abstract
Interaction of tidal flow with a complex topography and bathymetry including headlands, islands, coral reefs and shoals create a rich submesoscale field of tidal jets, vortices, unsteady wakes, lee eddies and free shear layers, all of which impact marine ecology. A unique and detailed view of the submesoscale variability in a part of the Great Barrier Reef lagoon, Australia, that includes a number of small islands was obtained by using a “stereo” pair of 2-m-resolution visible-band images that were acquired just 54 s apart by the WorldView-3 satellite. Near-surface current and vorticity were extracted at a 50-m-resolution from those data using a cross-correlation technique and an optical-flow method, each yielding a similar result. The satellite-derived data are used to test the ability of the second-generation Louvain-la-Neuve ice-ocean model (SLIM), an unstructured-mesh, finite element model for geophysical and environmental flows, to reproduce the details of the currents in the region. The model succeeds in simulating the large-scale (> 1 km) current patterns, such as the main current and the width and magnitude of the jets developing in the gaps between the islands. Moreover, the order of magnitude of the vorticity and the occurrence of some vortices downstream of the islands are correctly reproduced. The smaller scales (< 500 m) are resolved by the model, although various discrepancies with the data are observed. The smallest scales (< 50 m) are unresolved by both the model- and image-derived velocity fields. This study shows that high-resolution models are able to a significant degree to simulate accurately the currents close to a rugged coast. Very-high-resolution satellite oceanography stereo images offer a new way to obtain snapshots of currents near a complex topography that has reefs, islands and shoals, and is a potential resource that could be more widely used to assess the predictive ability of coastal circulation models.
Subject
High-resolution satellite imagery
SLIM
Submesoscale eddies
Unstructured mesh
To reference this document use:
http://resolver.tudelft.nl/uuid:c7b64478-05de-494b-a897-68a08bc547b8
DOI
https://doi.org/10.1007/s10236-017-1066-z
Embargo date
2018-05-22
ISSN
1616-7341
Source
Ocean Dynamics: theoretical, computational oceanography and monitoring, 67 (7), 897-913
Bibliographical note
Accepted author manuscript
Part of collection
Institutional Repository
Document type
journal article
Rights
© 2017 Philippe Delandmeter, Jonathan Lambrechts, George O. Marmorino, Vincent Legat, Eric Wolanski, Jean-François Remacle, Wei Chen, E.L.C. Deleersnijder