• Absolute reference: Galilean reference frame (without acceleration).
  • Admittance: the ocean's response, depending on the frequency, to the action of the generating force.
  • Age of the tide: time interval between the syzygy and the maximum range of tide that follows.
  • ALLENVI: Environmental alliance.
  • Altimetry: measurement of the height of water using spatial techniques.
  • Amphidromic points: points located at sea around which the tide wave appears to turn.
  • Amplitude: difference between the height of a high or low tide and the mean level. This term is often used in error to designate the range of tide.
  • Apparent time: true solar hour angle.
  • Argument number: method for designating the components of the tide, using a 6-figure number, making it possible to identify the astronomical parameters from which they are derived and deduce from them their period.
  • Ascending node: point at which the lunar orbit and the ecliptic intersect in the direction of movement of the Moon from the Southern to the Northern hemisphere.



  • Backrush current: current generated by the slope of the free surface, excluding the action of the tide.



  • CCI:  Chamber of Commerce and Industry.
  • CEA/LDG: Commissariat à l'Energie Atomique et aux Energies Alternatives / Laboratoire de Détection et de Géophysique (Atomic energy and alternative energy commission / Detection and geophysical laboratory).
  • CENALT: Centre national d'alerte aux tsunamis (national tsunami alert centre)
  • CETE: Centre d'études techniques de l'équipement (equipment technical study centre).
  • CETMEF: Centre d'Etudes Techniques Maritimes Et Fluviales (maritime and fluvial technical study centre
  • CG: Conseil Géneral (county council)
  • CGC: Commission de gestion de configuration (configuration management committee)
  • CGEDD: Conseil général de l'environnement et du développement durable (general council for the environment and sustainable development)
  • Chart datum: same as hydrographic datum.
  • CIL: Correspondant Informatique et Libertés (data protection coordinator).
  • CIMER: Comité interministériel de la mer (interministerial committee for the sea)
  • Civil time: mean time plus 12 hours.
  • CNES: Centre National d'Etudes Spatiales (national space study centre)
  • CNRS: Centre National de la Recherche Scientifique (national scientific research centre)
  • Coefficient: measurement of the amplitude of the tide expressed relative to the unit of height.
  • Concordance; species concordance: tidal analysis and prediction technique using the relations between the elements of a standard port and those of a secondary port.
  • Cotidal line: line on a chart passing through all the points at which high tide occurs at the same time.
  • CR: Conseil Régional (regional council)
  • CRATANEM: Centre régional d'alerte aux tsunamis pour l'Atlantique Nord-Est et la Méditerranée (Regional tsunami alert centre for the North East Atlantic and Mediterranean)
  • Current amplitude: maximum speed during a tidal cycle.
  • Current atlas: cartographic representation of the tidal current fields at various times.



  • Damping well: Device in a tidal observatory designed to flatten the area of water and reduce rapid movements due to waves and swell.
  • DDE: Direction Départementale de l'Equipement (county council infrastructure directorate)
  • DDEA 14 / SRAN: Direction Départementale de l'Equipement et de l'Agriculture du Calvados / Service Réglementation et activités nautiques (county council infrastructure and agricultural directorate for the Calvados department / Regulatory and nautical activities department)DDTM: Direction Départementale des Territoires et de la Mer (county council territorial and maritime department)
  • Declination: angle between the celestial body and the equatorial plane.
  • DéGéOM: Délégation générale de l'Outre-Mer (general delegation for overseas territories)
  • DGEC/ONERC: Direction générale de l'énergie et du climat / Observatoire national sur les effets du réchauffement climatique (general directorate for energy and climate / National observatory of the effects of global warming)
  • DGM: Direction générale de la météorologie (Madagascar) (general directorate for meteorology (Madagascar))
  • DGPR: Direction générale de la prévention des risques (general directorate for risk prevention)
  • Diurnal tide: one high water and one low water per day; the semi-diurnal components are negligible.
  • DMS: Demande de mise en service (commissioning request)
  • DMSOI: Direction de la Mer Sud Océan Indien (Directorate for the Sea – Southern Indian Ocean)
  • Doodson number: another name for an argument number.
  • DRE: Direction régionale de l'Equipement (regional infrastructure directorate)
  • DREAL - LR: Direction régionale de l'environnement, de l'aménagement et du logement - Languedoc-Roussillon (regional directorate for infrastructure, development and housing – Languedoc-Roussillon)
  • Drift current: current generated by the wind.
  • DSC: Direction de la Sécurité Civile (directorate of civil safety).



  • Ebb current or ebb: current accompanying the ebb tide.
  • Ebb: synonym of falling tide.
  • Ecliptic latitude: angle between the celestial body and the ecliptic plane.
  • Ecliptic longitude: angle between the orthogonal projection on the ecliptic of the direction of the celestial body and the direction of the vernal point.
  • Ecliptic: the Earth's orbit around the Sun or the Sun's apparent orbit viewed from the Earth.
  • Ellipsoid: mathematical surface defining a geodetic system based on the relative positions of points located on the Earth's surface.
  • Equation of time: difference between the mean time and the true time. Species: set of components whose frequencies are close to a given number of cycles per lunar day. we distinguish between species with long periods, diurnal and semi-diurnal species.
  • Equator: terrestrial great circle contained within the plane perpendicular to the polar axis.
  • Equinoctial point: intersection of the ecliptic plane and the equator.
  • Equinoctial spring tide: maximum amplitude of the semi-diurnal tide around the equinoxes.
  • Establishment of the port: time (true time) of high water on a day on which syzygy occurs at apparent noon.
  • EuroGOOS: European Global Ocean Observing System
  • Exceptional spring tide: semi-diurnal perigean equinoctial spring tide.
  • Extended argument number: Doodson number to which a 7th figure has been added, specifying whether the angular argument is associated with a positive or negative sine or cosine.



  • Falling tide: period during which the water level falls.
  • FAQ: Frequently Asked Questions (or Foire Aux Questions in French)
  • FFT: Fast Fourier Transform. Technique for representing a time signal in the spectral domain.
  • Fix sphere: representation system in which reference is made to celestial bodies by their direction on a sphere whose position is fixed with respect to the stars.
  • Flood current or flood: current accompanying the rising tide.
  • Flood: synonymous with rising tide.
  • Foreshore: Coastal strip between the levels achieved by the highest and lowest tides.



  • Generating force: resultant of the gravitational attractive force exerted by celestial bodies at a point on the Earth and the inertial driving force of a reference base associated with the Earth.
  • Generating potential: scalar magnitude from which the generating force is derived.
  • Geocentric zenith distance: zenith distance with respect to the centre of the earth.Historical data or metadata: Tide gauge data in non-digital format
  • Geodetic coefficient: element of the expression of the generating potential depending solely on the latitude.
  • Geographical coordinates: terrestrial latitude and longitude.
  • Geoid: equipotential surface of the Earth's gravitational field.
  • GLOSS: The Global Sea Level Observing System
  • GOES: Geostationary Operational Environmental Satellites
  • GPM: Grand Port Maritime (major maritime port)



  • Half tide: means of high and low waters.
  • Harmonic analysis: calculation of the harmonic constants of the tide.
  • Harmonic component: elementary tide wave, defined by its frequency, amplitude and phase.
  • Harmonic constant: the amplitude and situation of a harmonic component are harmonic constants of the said component.
  • HCR/DDPC-PF: Haut commissariat de la République de Polynésie française / Direction de la Défense et de la Protection Civile - Polynésie française (High commission of the Republic in French Polynesia / Directorate of defence and civil protection – French Polynesia)
  • HCR/DSC-NC: Haut commissariat de la République en Nouvelle-Calédonie / Direction de la Sécurité Civile - Nouvelle-Calédonie (High commission of the Republic in New Caledonia / Directorate of civil safety – New Caledonia)
  • High and low waters: extremes of the tide curve.
  • Hour angle: angle between the meridian half-plane of the position and the meridian half-plane of the celestial body, measured clockwise in the direction of the heavenly body.
  • Hydrographic datum: also called chart datum, common reference for nautical charts and tide tables for use by navigators.



  • IBI-ROOS: Ireland-Biscay-Iberia Regional Operational Oceanographic System
  • IDSC: Inspection de la défense et de la sécurité civile (Defence and civil safety inspectorate)
  • IFREMER: Institut Français de Recherche pour l'Exploitation de la MER (French research institute for the exploitation of the sea)
  • IGA: Inspection générale de l'administration (General admistration inspectorate)
  • IGF: Inspection générale des finances (General finance inspectorate)
  • IGN
  • IGN :  Institut national de l'information géographique et forestière ()
  • IIW: Institution interdépartementale des wateringues (Interdepartmental reclaimed land institution)
  • INPI: Institut national de la propriété industrielle (National institute for industrial property)
  • INSU: Institut National des Sciences de l'Univers (National institute for universal sciences)
  • Interaction component: Harmonic component generated by the non-linear effects of the ocean's response to the generating force.
  • IOC: Intergovernmental Oceanographic Commission
  • IPEV: Institut polaire français Paul Émile Victor (Paul Emile Victor French polar institute)
  • IPGP: Institut de physique du globe de Paris (Paris Earth physics institute)
  • IRD: Institut de Recherche pour le Développement (Research Institute for Development)
  • IRSN: Institut de Radioprotection et de Sûreté Nucléaire (Institute for radioprotection and nuclear safety)
  • ISDR: International Strategy for Disaster Reduction
  • ITRS: International Terrestrial Reference System.



  • JMA: Japan Meteorological Agency
  • JODC: Japanese Oceanographic Data Centre



  • Lagging tide: period in which the amplitude reduces.
  • Latitude: angle between the direction of the vertical of the position and the equatorial plane.
  • Least squares: calculation method making it possible to obtain an optimum estimate of a deterministic signal in the presence of noise.
  • Legendre polynomials: orthogonal polynomials. The generating potential is expressed in the form of a series of Legendre polynomials.
  • LEGOS: Laboratoire d'Études en Géophysique et Océanographie Spatiales (Space geophysics and oceanography studies laboratory).
  • Literal argument: argument number in which the figures have been replaced by letters.
  • Littoral circulation: resultant of the backrush current (gradient current) and the drift current near to the coast.
  • Longitude: angle between the meridian half-plane of the position and the origin meridian (the Greenwich meridian).
  • Low water: the lowest level reached by the sea during a tidal cycle.
  • Luminous probe: graduated tape, generally made from metal, equipped with a device indicating, by means of a light signal, when its end comes into contact with the surface of the water.
  • Lunar month: also known as the synodic revolution, it is the time interval between two full moons and two new moons.



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