Glossary
- Aliasing
spurious tidal frequency appearing in an analysis due to inadequate temporal sampling
- Amplitude
one half of the range of a tidal constituent
- Anomaly
angular distance between the perihelion and the position of a celestial body
- Apogee
point of an orbit where a celestial body is furthest to Earth
see Perigee
- Aphelion
point of an orbit where a celestial body is furthest from the sun
see Perihelion
- Ascending Node
point of an orbit where a celestial body intersects the ecliptic, and the latitude coordinate is increasing
- Barycenter
center of mass of a system of bodies
- Body Tide
see Solid Earth Tide
- Chandler Wobble
small, semi-periodic deviations in the motion of the pole of rotation
- Constituent
- Declination
angular distance of an astronomical body north or south of the celestial equator
- Descending Node
point of an orbit where a celestial body intersects the ecliptic, and the latitude coordinate is decreasing
- Diurnal Tide
tidal oscillations with a near-daily period
- Ecliptic
plane of the orbit of the Earth around the sun
- Ephemeris
table of positions and velocities of a celestial body at given instances in time
- Ephemerides
plural of Ephemeris
- Epoch
fixed point in time used as a reference value
- Equilibrium Tide
hypothetical tide produced solely by lunisolar gravitational forces under equilibrium theory
- Frequency
number of cycles in a unit time
- Geoid
equipotential surface coinciding with the ocean surface in the absence of astronomical or dynamical effects
- Harmonic Analysis
mathematical process by which the tides are separated into Harmonic Constituents
- Harmonic Constants
amplitude and phase of the Harmonic Constituents
- Harmonic Constituents
harmonic elements of the tide-producing force corresponding with a periodic change of relative position of the Earth, Sun and Moon
- Harmonic Prediction
Method of estimating tidal elevations and currents through a combination of the Harmonic Constituents
- Load Tide
elastic deformation of the solid Earth due to ocean and atmospheric tides
- Long Period Tide
tidal oscillations with periods much greater than one day
- Love and Shida Numbers
dimensionless parameters relating the vertical (h), horizontal (l) and gravitational (k) elastic responses to tidal loading
- Mean Tide
model with both direct and indirect permanent tidal effects retained
- Nodal Corrections
adjustments to the amplitudes and phases of harmonic constituents to allow for periodic modulations
- Nutation
short-period oscillations in the motion of the pole of rotation
- Obliquity
angle between the equatorial and orbital planes
- Ocean Tide
periodic movement in the level of sea surface due to gravitational and rotational forces
- Perigee
point of an orbit where a celestial body is closest to Earth
see Apogee
- Perihelion
point of an orbit where a celestial body is closest to the sun
see Aphelion
- Period
time it takes to make one complete revolution
- Permanent Tide
permanent deformation of the Earth caused by the presence of the Sun and the Moon
- Pole Tide
apparent tide due to variations in the Earth’s figure axis about its mean
- Semi-diurnal Tide
tidal oscillations with an approximate half-day period
- Solid Earth Tide
deformation of the solid Earth due to gravitational forces
- Tidal Current
horizontal movement of water due to periodic forces
- Tidal Species
classification of tidal constituents based on period
see Semi-diurnal Tide, Diurnal Tide, and Long Period Tide
- Tidal Stream
see Tidal Current
- Tide-Free
model with direct and indirect permanent tidal effects removed
- Vertical Datum
reference coordinate surface used for vertical positions
- Zero Tide
model with permanent direct tidal effects removed, but indirect loading effects retained