Journées GMMC – Toulon – 8 Juin 2016
New operational storm surge and wave forecasting configurations for French Overseas Departments S. Casitas(1,*), H. Michaud(1), A. Pasquet(1), L. Biscara(1), A. Dalphinet(2), P. Ohl(2), D. Jourdan(1), D. Paradis(2) (1) (2)
SHOM, France Météo-France, France
(*)
[email protected]
Objectives
Problematics
In the framework of HOMONIM (History, Observation and Modeling of sea levels) which is a joint project between the SHOM and Météo-France, that aims to improve the French waves and flooding by sea warning system (VVS, Météo-France), two new configurations for wave and circulation models on french overseas departments/territories are being developed: one for the Antilles/Guiana area and another one for the SW Indian Ocean, with a focus on the French Departments : Guadeloupe, Martinique, Guiana, and Mayotte, La Réunion at a resolution of a few hundred meters. These two operational systems will be set up by the end of 2016 in Météo-France operational chains.
•Lack of observations for models validation •Dissipation and wetting and drying in coral reef (Mayotte) and muddy environment (Guiana) •Wave / current / atmospheric interactions •Validity of numerical schemes and physical parameterization during cyclonic events •Bathymetry in the near shore zone highly variable (Guiana) •Limitation of the HYCOM barotropic model •Effects of vegetation and mangrove on dynamics •Large coverage for HYCOM model
HYCOM configuration for SW Indian Ocean -
First results of DUMILE hurricane
HYCOM barotropic (Bleck, 2002, Baraille and Filatoff, 1995) Regular grid (3.2km) GEBCO 2014 bathymetry (30’’) Tidal forcing from FES2012
Methodology •Collection of tidal gauges data •Tidal validation 1 year of tidal simulation Parametric test on bottom stress . Figure 1: Bathymetry of the SW Indian configuration •Storm surge validation Simulation of hurricane events (Hellen, Bejisa, Felleng, Dumile, Gamede, Dina) Atmospheric forcing : ALADIN (MASCA01), CEP (0.125), MesoNH with vortex repositioning (in test) Parametric tests on wind stress
Figure 5: Trajectory of DUMILE hurricane (December 2012 / January 2013)
Figure 3: Storm surge time evolution during DUMILE hurricane at Pointe des Galets (Reunion)
Figure 4: Storm surge from HYCOM during DUMILE hurricane
Figure 2: Tide validation at Dzaoudzi (Mayotte)
Sea state configurations for Guiana
An unstructured mesh with 30,509 nodes and a resolution of 10 km offshore and 200 m off the coast is built (Figure 6). The Wavewatch III © (WW3, Tolman 2014) model is implemented to extend on the coastal zones the MFWAM (Lefèvre et al., 2011) model already used operationally at a regional scale at Météo-France. The coverages of the mesh is contained in the area of the atmospheric high-resolution model Arome of Météo-France. Mesh was generated with Polymesh © (the mesh generator developped by A. Roland (T.U. Darmstadt)), with CFL and DZ criteria, and the use of polygons to refine the grid resolution over the areas of particular interest. Parameterization of TEST 451 (Ardhuin et al., 2010) with modifications in the wind source and dissipation terms from TEST 463 (Janssen et al. 2014), explained in Michaud et al. (2015) is tested. A NMB 100m dedicated to the area has been used (Biscara et al, 2015). The mesh is proved against real storm/hurricane cases of the last decade and also on a one-year simulation covering the period between July 2012 and July 2013. • Validation is performed by comparing simulation results with : Buoys of Météo-France and Cerema. Altimetric data for the one-year simulation (Jason 1 & 2, Saral) • Sensitivity tests: Atmospheric forcings and adjustment of βmax Bottom friction Current effect Wave damping in mud and also on mangrove coasts
Perspectives - Sea campaign - Downscalling around Mayotte / Reunion and near the coast of Guiana and Antilles - Wetting and drying scheme efficiency
Figure 6: Guiana bathymetry
Figure 7: Guiana mesh
Acknowledgements We thank the DGPR and the DGSCGC for financing this project, CEREMA for buoys data.
References
ARDHUIN F. et al. (2010). Semi-empirical dissipation source functions for ocean waves, part I : Definition, calibration and validation. Journal of Physical Oceanography, Vol. 40, pp 1917-1941. BARAILLE R., FILATOFF N. (1995). Modèle shallow-water multicouches isopycnal 297 de Miami. Rapport Technique 003/95, SHOM/CMO. BISCARA L. et al. (2015) Présentation de la gamme de MNT bathymétriques pour la modélisation océanographique (Projets HOMONIM et TANDEM), Colloque merIGéo, 24-26 novembre 2015, At Brest BLECK R. (2002). An oceanic general circulation model framed in hybrid isopycnic-301 Cartesian coordinates. Ocean Modelling, Vol. 4 (1), pp 55–88. 302 http://dx.doi.org/10.1016/S1463-5003(01)00012-9 JANSSEN P. et al. (2014). Final report of work package 1 of myWave EU project. LEFEVRE J.M., AOUF L., BATAILLE C., ARDHUIN F., QUEFFEULOU, P. (2009). Apport d'un nouveau modèle de vagues de 3° génération à Météo France. Actes de conférence des Ateliers de Modélisation de l’Atmosphère, 27-29 janvier 2009, Toulouse, France. TOLMAN et al. (2014) User manual and system documentation of WAVEWATCH III version 4.18
