Preprints
https://doi.org/10.5194/os-2020-79
https://doi.org/10.5194/os-2020-79
31 Aug 2020
 | 31 Aug 2020
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 Watelet, Jean-Marie Beckers, Jean-Marc Molines, and Charles Troupin

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.

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Sylvain Watelet, Jean-Marie Beckers, Jean-Marc Molines, and Charles Troupin
 
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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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, Jean-Marie Beckers, Jean-Marc Molines, and Charles Troupin

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, Jean-Marie Beckers, Jean-Marc Molines, and Charles Troupin

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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.