Publications scientifiques

Based on analysis of Global Positioning System (GPS) multipath signals recorded by a geodetic GPS receiver, GPS Reflectometry (GPS-R) has demonstrated unique advantages in relation to sea level monitoring. Founded on multipath reflectometry theory, sea level changes can be measured by GPS-R through spectral analysis of recorded signal-to-noise ratio data. However, prior to estimating multipath parameters, it is necessary to define azimuth and elevation angle mask to ensure the reflecting zones are on water.

Downscaling physical processes from a large scale to a regional scale 3D model is a recurrent issue in coastal processes studies. The choice of boundary conditions will often greatly influence the solution within the 3D circulation model. In some regions, tides play a key role in coastal dynamics and must be accurately represented. The Bay of Biscay is one of these regions, with highly energetic tides influencing coastal circulation and river plume dynamics.

Radar altimetry was initially designed to measure the marine geoid. Thanks to the improvement in the orbit determination from the meter to the centimeter level, this technique has been providing accurate measurements of the sea surface topography over the open ocean since the launch of Topex/Poseidon in 1992. In spite of a decrease in the performance over land and coastal areas, it is now commonly used over these surfaces. This study presents a semi-automatic method that allows us to discriminate between acquisitions performed at high tides and low tides.

Shield volcanoes are described as low-angle edifices built primarily by the accumulation of successive lava flows. This generic view of shield volcano morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galápagos). Here, the morphometry of 158 monogenetic and polygenetic shield volcanoes is analyzed quantitatively from 90-meter resolution SRTM DEMs using the MORVOLC algorithm.

Monitoring changes in coastal sea levels is necessary given the impacts of climate change. Information on the sea level and its changes are important parameters in connection to climate change processes. In this study, radar altimetry data from successive satellite missions, European Remote Sensing-2 (ERS-2), Jason-1, Envisat, Jason-2, and Satellite with ARgos and ALtiKa (SARAL), were used to measure sea surface heights (SSH). Altimetry-derived SSH was validated for the southern Bay of Biscay, using records from seven tide gauges located along the French Atlantic coast.

Coastal flooding due to surge events represents natural hazards with huge potential consequences for coastal regions. Sea level time series display variations on a large range of timescales, with a deterministic component associated with tidal variations and a stochastic component primarily associated with meteorological forcing, the non-tidal residual. The deterministic component can be evaluated using a model taking into account astronomical forcing and topographic information.

Posidonia oceanica plays a significant role in the stabilization and protection of the coast in Gulf of Giens. Unfortunately, its distribution has been declining remarkably due to both anthropogenic interventions and natural factors. The present study focuses on the numerical simulation of the presence of Posidonia as well as the influence of its disappearance on hydrodynamics and sediment transport along Alamanarre beach.

Automatic sea-level measurements in Nouméa, South Pacific, started in 1957 for the International Geophysical year. Data from this location exist in paper record for the 1957–1967 period, and in two distinct electronic records for the 1967–2005 and 2005–2015 period. In this study, we digitize the early record, and established a link between the two electronic records to create a unique, nearly 60 year-long instrumental sea-level record. This work creates one of the longest instrumental sea-level records in the Pacific Islands.

La façade maritime méditerranéenne est bordée par plusieurs départements littoraux sur lesquels des enjeux de gestion du Domaine Public Maritime naturel (DPM) forts existent. La délimitation du DPM est complexe et un éventail de techniques est disponible. Afin d’apporter des éléments d’appréciation, le Cerema s’est penché sur l’approche probabiliste qui vise à estimer l’action des vagues au niveau du rivage à partir des données hydrauliques disponibles. Les périodes de retour associées au niveau d’eau avec l’action des vagues sont étudiées pour une plage à enjeux de Méditerranée.