On the improvement of high resolution AROME winds for operational wave forecast under cyclonic conditions : validation with altimeters wave data

Lotfi Aouf (Division Marine et Océanographie Météo-France, France)

CoAuthors

Alice Dalphinet (Meteo-France, France); Ghislain Faure (CNRM/GMAP/Meteo-France, France); Hervé Giordani (CNRM/GMGEC/Meteo-France, France)

Event: 2017 Ocean Surface Topography Science Team Meeting

Session: Application development for Operations

Presentation type: Type Poster

Wind forcing at the ocean surface plays a key role for catching accurate initial conditions of wind waves and swell propagation in cyclonic conditions. It is clearly a challenge for weather prediction centres for improving the wind forcing to waves and storm surge operational models. To this end the high resolution atmospheric system AROME-OM of Meteo-France dedicated for regional domains (west-indies, La Reunion and French Polynesia) will be upgraded in September 2017. In this version the AROME-OM system is forced by 1-D ocean mixed layer with initial conditions of sea surface temperature (SST) provided by the Mercator operational ocean model. The goal of this study is to investigate the impact of two wind forcing provided by the upgraded AROME-OM atmospheric system on the wave forecast during cyclones and hurricane events. The first wind forcing is using only the sea surface temperature from operational Mercator ocean system, while the second wind forcing is issued from AROME-OM model forced by 1-d ocean mixed layer with SST from mercator system as initial conditions.
Two events have been investigated for this study : cyclone Fantala in the indian ocean (March 2016) and hurricane Matthew (October 2016) in the Carribean sea. Regional wave models MFWAM with 10 km of resolution are forced by AROME-OM hourly winds and runs have been performed for analysis and forecast periods. A base line run of the wave model MFWAM with wind field from old version of AROME-OM system is also performed for these two events.
The validation with altimeters wave heights shows a significant improvement in the first 0-5 hours of analysis from the run using upgraded winds from AROME-OM with SST of Mercator ocean system. The scatter index of significant wave height is well reduced by 17 % for the cyclone Fantala. The use of 1-D ocean mixed layer improves the significant wave heights during the forecast period. altimeters tracks passing over the domain of cyclone Fantala indicates a good correction of the peak position of significant wave height when using the upgraded AROME-OM winds. Further results will be discussed and commented for hurricane Matthew hurricane.
 

Poster show times:

RoomStart DateEnd Date
Concerto Ballroom Thu, Oct 26 2017,14:00 Thu, Oct 26 2017,18:00
Lotfi Aouf
Division Marine et Océanographie Météo-France
France
lotfi.aouf@meteo.fr