Preprints
https://doi.org/10.5194/os-2020-79
https://doi.org/10.5194/os-2020-79

  31 Aug 2020

31 Aug 2020

Review status: this preprint was under review for the journal OS but the revision was not accepted.

Properties of baroclinic Rossby waves in the North Atlantic from eddy-resolving simulations of ocean circulation

Sylvain Watelet1,a, Jean-Marie Beckers1, Jean-Marc Molines2, and Charles Troupin1 Sylvain Watelet et al.
  • 1Department of Astrophysics, Geophysics and Oceanography, GeoHydrodynamics and Environment Research Unit, FOCUS Research Unit, University of Liège, Liège, Belgium
  • 2Université Grenoble Alpes/CNRS/IRD/G-INP, IGE, Grenoble, France
  • acurrent address: Observation Scientific Service, Royal Meteorological Institute, Brussels, Belgium

Abstract. The teleconnections between the North Atlantic Oscillation (NAO) and the variability of the Gulf Stream (GS) were extensively studied these last years, often exhibiting time delays between both phenomena. These time lags, usually ranging between 0–2 years, are sometimes explained by the hypothesis of baroclinic Rossby waves generated by the NAO in the central North Atlantic (NA) and travelling westward before interacting with the GS. In this study, we use a numerical hindcast at an eddy-resolving resolution (1/12°) from the DRAKKAR project to examine the occurrence and properties of such Rossby waves between 1970–2015, thus including a large pre-TOPEX/Poseidon period. Through the use of a two-dimensional Radon Transform (2D-RT) on Hovmöller diagrams of the Sea Surface Height (SSH), a methodology easily portable to other oceanic model outputs, we show evidence of baroclinic Rossby waves travelling at 39° N at a speed of 4.17 cm s−1. This is the first time Rossby waves are found that much north during such an extended period. These results are consistent with the time lags observed between the NAO and the GS transport while the GS latitudinal shifts might obey additional processes.

Sylvain Watelet et al.

 
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Status: closed
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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Sylvain Watelet et al.

Data sets

SSH data set used for Rossby Wave Analysis, extraction from ORCA12.L46-MJM189 DRAKKAR simulation Jean-Marc Molines https://doi.org/10.5281/zenodo.3968801

Detrended SSH data set used for Rossby Wave Analysis, extraction at 39N from ORCA12.L46-MJM189 DRAKKAR simulation Sylvain Watelet https://doi.org/10.5281/zenodo.3968885

Model code and software

meom-configurations/ORCA12.L46-MJM189: Rossby wave paper version Jean-Marc Molines https://doi.org/10.5281/zenodo.3968307

Sylvain Watelet et al.

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Short summary
In this study, we use a numerical hindcast at high resolution (1/12°) to examine the occurrence and properties of Rossby waves in the North Atlantic between 1970–2015. We show evidence of Rossby waves travelling at 39° N at a speed of 4.17 cm s−1. These results are consistent with baroclinic Rossby waves generated by the North Atlantic Oscillation in the central North Atlantic and travelling westward before interacting with the Gulf Stream transport with a time lag of about 2 years.