Observations of large infragravity wave runup at Banneg Island, France

• Published in: Geophysical Research Letters
• Main Authors: Sheremet, Alex, Staples, Tracy, Ardhuin, Fabrice, Suanez, Serge, S., Fichaut, Bernard
• Other Authors: Engineering School for Sustainable Infrastructure and Environment (ESSIE), University of Florida Gainesville (UF), Laboratoire d'Océanographie Spatiale (LOS), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Littoral, Environnement, Télédétection, Géomatique (LETG - Brest), Littoral, Environnement, Télédétection, Géomatique UMR 6554 (LETG), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université d'Angers (UA)-École Pratique des Hautes Études (EPHE), Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université de Brest (UBO)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut de Géographie et d'Aménagement Régional de l'Université de Nantes (IGARUN), Université de Nantes (UN)-Université de Nantes (UN)-Université de Caen Normandie (UNICAEN), Université de Nantes (UN)-Université de Nantes (UN), FP7-ERC young investigator grant 240009 - IOWAGA project; U.S. Oce of Naval Research grant N00014-10-1-0383 (U.S. National Ocean Partnership Program)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: infragravity waves; trapped waves; storm waves; [PHYS.PHYS.PHYS-AO-PH]Physics [physics]/Physics [physics]/Atmospheric and Oceanic Physics [physics.ao-ph]; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; North Atlantic
• Online Access: https://hal.science/hal-00954313; https://doi.org/10.1002/2013GL058880

International audience On Banneg Island, France, very high water-level events (6.5 m above the astronomical tide) have been observed on the western cliff, exposed to large swells from the North Atlantic. The analysis of hydrodynamic measurements collected during the storm of 10 February 2009 shows unusually high (over 2 m) infragravity wave runup events. By comparing runup observations to measurements in approximately 7 m of water and numerical simulations with a simplified nonlinear model, two distinct infragravity bands may be identified: an 80 s infragravity wave, produced by nonlinear shoaling of the storm swell; and a 300 s wave, trapped on the intertidal platform of the island and generating intermittent, low-frequency inundation. Our analysis shows that the 300 s waves are a key component of the extreme water levels recorded on the island.