A 30-m scale modeling of extreme gusts during Hurricane Irma (2017) landfall on very small mountainous islands in the Lesser Antilles

• Main Authors: Cécé, Raphaël, Bernard, Didier, Krien, Yann, Leone, Frédéric, Candela, Thomas, Péroche, Matthieu, Biabiany, Emmanuel, Arnaud, Gael, Belmadani, Ali, Palany, Philippe, Zahibo, Narcisse
• Format: Text
• Language: English
• Published: 2020
• Subjects: Martin Islands
• Online Access: https://doi.org/10.5194/nhess-2020-241; https://nhess.copernicus.org/preprints/nhess-2020-241/

In view of the high vulnerability of the Lesser Antilles small islands to cyclonic hazards, realistic very fine scale numerical simulation of hurricane-induced winds is essential to prevent and manage risks. The present innovative modeling aims at combining the most realistic simulated strongest gusts driven by tornado-scale vortices within the eyewall and the most realistic complex terrain effects. The Weather Research and Forecasting (WRF) model with the Nonlinear Backscatter and Anisotropy (NBA) Large Eddy Simulation (LES) configuration was used to reconstruct the devastating landfall of category 5 Hurricane Irma (2017) on Saint Barthélemy and Saint Martin islands. The results pointed out that the 30-m scale seems necessary to simulate intense 400-m scale vortices leading to extreme peak gusts like 132 m s −1 over sea. Risk areas associated with terrain gust speed-up factors greater than one have been identified for the two islands. The comparison between the simulated gusts and the remote sensing building damages highlighted the major role of structure strength linked with the socio-economic development of the territory. The present modeling method could be easily extended to other small mountainous islands to improve the understanding of observed past damages and to develop safer urban management and appropriate building standards.