Investigating the protective role of the barrier reef and the energy transmitted from the open sea to the Raroia lagoon under rough sea conditions.
The study of waves transmitted in the lagoon during strong offshore swells highlights large-scale resonant modes (seiches type) whose impact on erosion and submersions is well established. Understanding these modes in a context of rising oceans is therefore a major challenge.
The MAEVA-SWOT campaign investigated the large-scale slow modes in the lagoons using the SWOT KaRin instrument combined with in situ measurements. These modes are measurable by pressure gauges which will be deployed in the lagoon.
The atoll of Raroia (16°01′S-142°26′O) is located on the SWOT one-day orbit. This atoll is of very regular shape, ideal for the study of eigen modes. Its dimensions of 30 km by 10 km provides a well-suited surface for the SWOT study of large-scale modes. The instrumentation of the Raroia lagoon took place at the end of February 2023.
The wave gauges recorded pressure from April to August 2023, and were recovered in autumn 2023. These measurements are being compared with SSH (Sea Surface height) measurements from the KaRin instrument.
Principal investigators: Emmanuel Dormy (DMA-ENS), Ludivine Oruba (LATMOS-Sorbonne Univerisité), Serge Planes (CRIOBE-EPHE).
Contact point for the study site: Emmanuel Dormy (Emmanuel.Dormy@ens.fr).
Publications: Rebouillat, E., Oruba, L., Hopuare, M., Planes, S. and Dormy, E., 2026. SWOT sheds light on seiche oscillations within atoll islands. Geophysical Research Letters, 53(4), p.e2025GL119801. https://doi.org/10.1029/2025GL119801