Circulation around La Reunion and Mauritius islands in the south-western Indian Ocean: A modeling perspective

Type Article
Date 2014-03
Language English
Author(s) Pous Stephane1, 2, 3, Lazure Pascal4, Andre Gael5, Dumas Franck4, Halo Issufo2, 6, Penven Pierrick3, 7
Affiliation(s) 1 : Univ Paris 06, CNRS, LOCEAN Lab, Sorbonne Univ,IRD,MNHN, Paris, France.
2 : Univ Cape Town, Dept Oceanog, ZA-7925 Cape Town, South Africa.
3 : Univ Cape Town, IRD, LMI ICEMASA, ZA-7925 Cape Town, South Africa.
4 : Inst Francais Rech Exploitat Mer, Plouzane, France.
5 : Altran Ouest, Brest, France.
6 : Univ Cape Town, Nansen Tutu Ctr Marine Environm Res, ZA-7925 Cape Town, South Africa.
7 : IRD, Lab Phys Oceans, Plouzane, France.
Source Journal of Geophysical Research-Oceans (0148-0027) (Amer Geophysical Union), 2014-03 , Vol. 119 , N. 3 , P. 1957-1976
DOI 10.1002/2013JC009704
WOS© Times Cited 8
Note This work is a contribution to the HYDRORUN project, funded from 2009 to 2012 by the European Union (ERDF), IFREMER, the Conseil R egional de la R eunion, the Office de l’Eau de La Reunion and the DEAL Reunion.
Keyword(s) ocean circulation, hydrodynamic model, La Reunion, eddies, Rossby waves
Abstract The objective of this study is to document the circulation in the vicinity of La Reunion and Mauritius islands, i.e., within 500 km offshore, on the intraseasonal time scale, using a high-resolution realistic modeling strategy. The simulated sea level anomalies, water mass properties, and large-scale circulation compare favorably with satellite and in situ observations. Our high-resolution simulation suggests that the currents around the islands are maximal locally, oriented southwestward, to the southeast of both islands which is not visible in low-resolution satellite observations. It also highlights the high degree of variability of the circulation, which is dominated by westward propagating features. The predominant time scale of variability is 60 days. This coincides with the period of a barotropic mode of variability confined to the Mascarene Basin. The characteristics of the westward propagating anomalies are related to baroclinic Rossby waves crossing the Indian Ocean but only in the long-wave resting ocean limit. Tracking those anomalies as eddies shows that they also have a meridional tendency in their trajectory, northward for cyclones and southward for anticyclones, which is consistent with previous studies. Sensitivity experiments suggest that they are predominantly advected from the east, but there is also local generation in the lee of the islands, due to interaction between the circulation and topography. Key Points Circulation around both islands is dominated by westward propagating features The predominant time scale of variability of currents and SSH is 60 days There is local generation of eddies in the lee of the islands due to topography
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Pous Stephane, Lazure Pascal, Andre Gael, Dumas Franck, Halo Issufo, Penven Pierrick (2014). Circulation around La Reunion and Mauritius islands in the south-western Indian Ocean: A modeling perspective. Journal of Geophysical Research-Oceans, 119(3), 1957-1976. Publisher's official version : https://doi.org/10.1002/2013JC009704 , Open Access version : https://archimer.ifremer.fr/doc/00195/30624/