Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 95 : tidal range for mean neap tides for average atmospheric conditions..

Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 20 : minimum tidal range for average atmospheric conditions..

Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 95 : maximal tidal range for average atmospheric conditions..

Tidal ranges on the French coasts of the Channel and the Atlantic for a coefficient of 95 : tidal range for mean spring tides for average atmospheric conditions..

This product shows the international distribution of types of tides. Four types of tides exist, and are classified based on the number and height of high and low waters each day: semi-diurnal tide: two high tides and two low tides with approximately the same height are recorded each day. Mixed tides with diurnal inequality: two high and low tides are recorded daily (just like with semi-diurnal tides), however the heights of the high and low waters vary significantly over the same day. Diurnal tides: one single high tide and one single low tide are recorded each day. Composite: tides can be diurnal or semi-diurnal or mixed.

The Shom uses a 2D barotropic version of the HYCOM code (https://hycom.org/) to compute water level /surge forecasts (astronomical tides and meteorological surges) for the Atlantic, Mediterranean, Antilles-Guyane and Indian Ocean domains. The configurations use curvilinear grid with resolutions of several km offshore and ranging from 1.5km to around 500m on the french mainland coasts and the Antilles-Guyana coast. A downscaling by nesting allows a resolution of 800m to 200m over the Indian domain. These models have been adapted by the Shom to be operable in coastal areas by taking into account, in particular, the tide and high resolution bathymetry in these areas (from 100m for DTMs of facade to 20m for coastal DTMs) using Litto3D surveys by airborne LIDAR. The models are operated by Météo-France and the Shom in the framework of the HOMONIM project for the coastal flood/wave warning system.

The Tidal stream atlas netcdf product – Strait of Dover provides tidal current data for an area stretching from the coast of Flanders east of Dunkirk to Saint-Valery-en-Caux. The product consists of four gridded files with different spatial resolutions covering the Strait of Dover area (overall view at 500 m) and the geographical areas of the ports of Dunkirk (250 m), Calais (250 m) and Boulogne-sur-Mer (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.

The Tidal stream atlas netcdf product – Western Brittany provides tidal current data for an area stretching from the northern coast of Brittany (Porsguen) to the south of Penmarc'h. The product consists of four gridded files with different spatial resolutions covering the Finistère area (overall view at 500 m) and the geographical areas of the Iroise Sea (250 m), Brest bay (100 m) and Brest harbour (30 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.

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.

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.