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Testing Munk's hypothesis for submesoscale eddy generation using observations in the North Atlantic

Buckingham, Christian E. and Khaleel, Zammath and Lazar, Ayah and Martin, Adrian P. and Allen, John T. and Naveira Garabato, Alberto C. and Thompson, Andrew F. and Vic, Clément (2017) Testing Munk's hypothesis for submesoscale eddy generation using observations in the North Atlantic. Journal of Geophysical Research. Oceans, 122 (8). pp. 6725-6745. ISSN 2169-9275. https://resolver.caltech.edu/CaltechAUTHORS:20170926-085105572

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Abstract

A high-resolution satellite image that reveals a train of coherent, submesoscale (6 km) vortices along the edge of an ocean front is examined in concert with hydrographic measurements in an effort to understand formation mechanisms of the submesoscale eddies. The infrared satellite image consists of ocean surface temperatures at ~390 m resolution over the midlatitude North Atlantic (48.69°N, 16.19°W). Concomitant altimetric observations coupled with regular spacing of the eddies suggest the eddies result from mesoscale stirring, filamentation, and subsequent frontal instability. While horizontal shear or barotropic instability (BTI) is one mechanism for generating such eddies (Munk's hypothesis), we conclude from linear theory coupled with the in situ data that mixed layer or submesoscale baroclinic instability (BCI) is a more plausible explanation for the observed submesoscale vortices. Here we assume that the frontal disturbance remains in its linear growth stage and is accurately described by linear dynamics. This result likely has greater applicability to the open ocean, i.e., regions where the gradient Rossby number is reduced relative to its value along coasts and within strong current systems. Given that such waters comprise an appreciable percentage of the ocean surface and that energy and buoyancy fluxes differ under BTI and BCI, this result has wider implications for open-ocean energy/buoyancy budgets and parameterizations within ocean general circulation models. In summary, this work provides rare observational evidence of submesoscale eddy generation by BCI in the open ocean.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1002/2017JC012910DOIArticle
http://onlinelibrary.wiley.com/doi/10.1002/2017JC012910/abstractPublisherArticle
ORCID:
AuthorORCID
Buckingham, Christian E.0000-0001-9355-9038
Martin, Adrian P.0000-0002-1202-8612
Thompson, Andrew F.0000-0003-0322-4811
Vic, Clément0000-0003-1290-9353
Additional Information:© 2017 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. Received 24 MAR 2017; Accepted 18 JUL 2017; Accepted article online 24 JUL 2017; Published online 28 AUG 2017. We wish to thank the Editor and two reviewers for superb feedback. We are grateful to P. Cornillon, S. Saux Picart, and H. Roquet for help locating NRT MSG-3 SST measurements. We also thank J. Vasquez, T. McKnight, and E. Maturi for discussions regarding data dropouts in MSG-2 data. We thank L. Brannigan and N. Lucas for access to processed ADCP measurements. We thank D. Mountfield of NMF for discussions regarding SeaSoar. Finally, the following individuals provided helpful feedback: S. Henson, Y. Firing, J. Callies, M. Bell, K. Nicholls, S. Griffies, S. Smith, J. Taylor, and D. Whitt. C.B. would also like to thank G. Roullet and colleagues for conversations in Brest, France (November 2015) and S. Belcher for encouragement to work on this project. We would like to specifically acknowledge the contributions of Z.K. His efforts to obtain the satellite imagery and initial analysis during his MSc paved the way for this and subsequent studies. C.B. and Z.K. conducted the linear instability analysis and wrote much of the manuscript. A.M. and J.A. collected, processed, and analyzed the SeaSoar II data. All other authors contributed to ideas central to the manuscript and helped frame the study. Lastly, we congratulate Walter Munk on 100 years. Amazing. VIIRS data were obtained from NOAA Comprehensive Large Array-Data Stewardship System (CLASS), MSG-03 SST were obtained from CERSAT/IFREMER, and SSH measurements were obtained from AVISO/CNES. SeaSoar II specifications are available from Chelsea Technologies Group (http://www.chelsea.co.uk). This research was made possible by grants from the Natural Environmental Research Council (NE/I019999/1, NE/I019905/1) and National Science Foundation (NSF-OCE 1155676), support for ZK from the Ministry of Environment and Energy, Maldives, and a small computing grant from the University of Southampton.
Funders:
Funding AgencyGrant Number
Natural Environmental Research Council (NERC)NE/I019999/1
Natural Environmental Research Council (NERC)NE/I019905/1
NSFOCE-1155676
Ministry of Environment and Energy (Maldives)UNSPECIFIED
University of SouthamptonUNSPECIFIED
Subject Keywords:eddies; submesoscale; baroclinic; infrared; instabilities; front
Issue or Number:8
Record Number:CaltechAUTHORS:20170926-085105572
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170926-085105572
Official Citation:Buckingham, C. E., Z. Khaleel, A. Lazar, A. P. Martin, J. T. Allen, A. C. Naveira Garabato, A. F. Thompson, and C. Vic (2017), Testing Munk's hypothesis for submesoscale eddy generation using observations in the North Atlantic, J. Geophys. Res. Oceans, 122, 6725–6745, doi:10.1002/2017JC012910
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81826
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:26 Sep 2017 16:10
Last Modified:03 Oct 2019 18:47

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