1. University of Toulouse, LEGOS (CNES/CNRS/IRD/UPS), 31400 Toulouse, France
2. International Chair in Mathematical Physics and Applications (ICMPA-UNESCO CHAIR), University of Abomey-Calavi, Abomey-Calavi BP 2549, Benin
3. Institut de Recherches Halieutiques et Océanologiques du Bénin (IRHOB), Cotonou BP 1665, Benin
4. LOPS, University of Brest, CNRS, IRD, Ifremer, IUEM, 29238 Brest, France
5. Laboratory of Geosciences, Environment and Applications (LaGEA), National University of Sciences Technology, Engineering and Mathematics (UNSTIM), Abomey-Calavi BP 2282, Benin