The Tidal stream atlas netcdf product – Seine Bay provides tidal current data for an area stretching from Fecamp at the east of the area to Cherbourg at the west. The product consists of two gridded files with different spatial resolutions covering the Seine Bay area (overall view at 500 m) and the geographical area of Le Havre harbour (250 m). The U and V velocities of the tidal currents depend on the tidal conditions considered at mean neap and spring tidal rates. The data are provided in m/s for the surface layer. The times are given in relation to high tide or low tide at the reference port chosen in the area and are provided from 6 hours before to 6 hours after that reference.

This service allows users to view surface tidal current predictions calculated from the analysis of a high-resolution hydrodynamic simulation projected onto a 2 km grid.

This service allows users to view surface tidal current predictions calculated from the analysis of a high-resolution hydrodynamic simulation projected onto a 30 m grid. This service was built by Shom and funded by French CCI Métropolitaine Bretagne Ouest in the frame of the Atlantic Blue Port project of <a href="https://www.atlanticarea.eu" target="_blank">Interreg Atlantic Area</a> european program.

The Tidal stream atlas netcdf product – Northern Brittany provides tidal current data for an area stretching from Tregastel at the east of the area to Porsguen at the west. The product consists of two gridded files with different spatial resolutions covering the Northern Brittany area (overall view at 500 m) and the geographical area of the port of Roscoff (250 m). The U and V velocities of the tidal currents depend on the tidal conditions considered at mean neap and spring tidal rates. The data are provided in m/s for the surface layer. The times are given in relation to high tide at the reference port chosen in the area and are provided from 6 hours before to 6 hours after that reference.

This service allows users to view surface tidal current predictions calculated from the analysis of a high-resolution hydrodynamic simulation projected onto a 250 m grid. This service was built by Shom and funded by French CCI Métropolitaine Bretagne Ouest in the frame of the Atlantic Blue Port project of <a href="https://www.atlanticarea.eu" target="_blank">Interreg Atlantic Area</a> european program.

The Tidal stream atlas netcdf product – Northern Brittany provides tidal current data for an area stretching from Tregastel at the east of the area to Porsguen at the west. The product consists of two gridded files with different spatial resolutions covering the Northern Brittany area (overall view at 500 m) and the geographical area of the port of Roscoff (250 m). The U and V velocities of the tidal currents depend on the tidal conditions considered at mean neap and spring tidal rates. The data are provided in m/s for the surface layer. The times are given in relation to high tide at the reference port chosen in the area and are provided from 6 hours before to 6 hours after that reference.

Bathymetric datasets are an extraction of surveys belonging to the Shom public database. For depth up to 50m, the vertical precision of soundings varies from 30cm to 1m and the horizontal precision varies from 1 to 20m. In deep ocean, the vertical precision is mainly around 1 or 2% of the bottom depth. It is sometimes more, it depends on the technology used. The data are referenced to ZH which is assimilated to LAT. Data are corrected for sound velocity variations. <br /> October 27 2025 version

Litto3D is a unique and continuous land-sea database which can provide 3D models of the shape and location of French coastal terrain. A line separates sea and land data acquisition zones, and the associated survey readings obtained using bathymetric lidar technologies or multibeam echosounders for sea readings and airborne lidar topographical surveys for land readings, with 300 m overlap. Litto3D digital models are available in two formats: a set of 3D points and a qualified terrain mesh.

Litto3D is a unique and continuous land-sea database which can provide 3D models of the shape and location of French coastal terrain. A line separates sea and land data acquisition zones, and the associated survey readings obtained using bathymetric lidar technologies or multibeam echosounders for sea readings and airborne lidar topographical surveys for land readings, with 300 m overlap. Litto3D digital models are available in two formats: a set of 3D points and a qualified terrain mesh.

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.