The product "BathyElli surfaces v2.1" contains the surface realisation of the ellipsoidal height at the reference date of 1 January 2000 of the characteristic tidal levels corresponding to : - Highest Astronomical Tide (HAT): "BathyElli v2.1 HAT / ell" ; - Mean Sea Levels (MSL): "BathyElli v2.1 MSL / ell"; - Lowest Astronomical Tide (LAT): "BathyElli v2.1 LAT / ell"; - Chart Datum (CD) vertical sea level reference for each tidal zone: "BathyElli v2.1 HZ / ell".

The product "Distribution of the submarine dunes of the French continental shelf" contains digital vector data provided as 2D linear objects representing the crest of submarine dunes digitized from bathymetric surveys conducted by the Shom. When several surveys have been carried out on the same area or dune, the product contains the information from all the surveys. However, the data displayed on data.shom.fr is limited to the information from the most recent survey.

The product is a digital solution showing superficial sediments on the sea floor along coasts in mainland France.

Wave forecasting models allow the representation of sea states based on a spectral resolution at the global scale or at the scale of ocean basins. This code calculates the evolution of the sea state by decomposing it into a wave spectrum that propagates in different directions and with different periods. During the propagation, the wave energy is increased or decreased by the effects of wind, breaking waves and energy exchanges between the different components. The wave forecasts available on data.shom.fr are calculated with 2 different types of models: MFWAM for the offshore domain (resolution from 0.5° to 0.1°) and Wavewatch III ® (WW3) for the coastal domain (resolution from 2' to 200m). MFWAM is a sea state forecasting model (wind wave and swell) derived from the third generation WAM code (WAMDI Group, 1988). Wavewatch III ® (WW3) is developed in a collaboration between the United States Weather Service (NOAA/NCEP), Shom, the University of Darmstadt in Germany, and other partners. The forecasts published on data.shom.fr are issued from the parameterization carried out and optimized by the Shom and Météo-France within the framework of the Homonim project (national coastal flood/wave/storm warning system).

The land-sea limit corresponds to the Highest Astronomical Tide (HAT) in the case of a tide of coefficient 120 and under normal meteorological conditions (no offshore wind and mean atmospheric pressure of 1013 hPa). This geometric line is naturally defined as the intersection of a HAT model (extended to the coast and the top end of the upper estuary) based on the available Bathyelli surfaces, and a high-resolution digital terrain model of the coastal area. It corresponds to the highest limit of the intertidal area and takes into account, when they exist, the 3 administrative maritime limits which are: the transversal limit of the sea (LTM), the salt water limit (LSE) and the limit of maritime jurisdiction (LAM). This limit is measured (quoted) in relation to the local hydrographic chart datum and to the levels of reference for France (IGN69 and IGN78 for Corsica). Relations to other levels of reference (mean sea level and ellipsoid) are known. The land-sea limit product, mainly results from the exploitation of the two products Litto3D®/RGEALTI® and Bathyelli, and represents, with a metric resolution (1 to 5 metres), this theoretical entity by a set of 2D polylines describing the nature of the coast (artificial or natural, rocky or sandy, steep or flat, etc.). The method used for calculating the land-sea limit makes it possible to produce a continuous, homogeneous and spatially coherent limit on the entire French metropolitan coastal area.

Sea bed sediment maps for the 4 marine sub-regions prepared as part of the initial evaluation of the MSFD (Marine Strategy Framework Directive).

Images numériques non géoréférencées au format JPEG2000 des minutes de levés hydrographiques anciens issues des archives historiques du Shom. Ces minutes hydrographiques (plans bathymétriques et topographiques) ont été réalisés lors de ses travaux de mesures en mer depuis le début du XIXe siècle à nos jours.

Pour modéliser les niveaux d'eau (notamment la marée astronomique et les surcotes météorologiques), le Shom utilise une version barotrope (2D) du code HYCOM (https://hycom.org/) configuré sur 2 domaines : Atlantique et Méditerranée. Les configurations ont été paramétrisées avec une bathymétrie fine et une grille curviligne à résolution variable allant de 2km au large à 500m à la côte. Ces modèles ont été adaptés par le Shom à la modélisation des zones côtières par la prise en compte, notamment, de la marée et de la bathymétrie haute résolution en zone côtière (de 100m pour les MNT de façade à 20m pour les MNT littoraux) utilisant notamment les levés Litto3D par LIDAR aéroportés. Les modèles sont opérés par Météo-France et le Shom dans le cadre de la vigilance Vagues-Submersions.

The georeferenced digital image solution for the nautical chart is a digital conversion of the corresponding printed nautical chart produced by Shom or its legends, with georeferencing indications and including miscellaneous text.