Example of geophysical information extracted from altimetry (around Italy). (Credits University of Calgary).

Geodesy and geophysics

Geophysics is the study of the substances that make up the Earth and the physical processes occurring on, in and above it.
Electromagnetic waves emitted and received by the satellite do not penetrate far beneath the sea surface. Altimetry satellites do measure range from the satellite to the surface, but the estimated sea surface height also comprises the cumulative impact of many phenomena over the whole water column. Thus we can deduce from these measurements what's happening in the depths.

 

 

Altimetry became an essential contribution to be used to study the Earth's shape and size, gravity anomalies (geodesy), seafloor relief (bathymetry), tectonic plate motion and rifts (geophysics), etc. Although often linked to plate tectonics, tsunamis are very different, transient phenomena. However, their impact on the sea surface can be seen by altimeters in some cases, thus helping the study of their propagation.

On this theme, you can consult :

  • Bathymetry

    Dense satellite altimeter measurements can be used in combination with sparse measurements of seafloor depth to construct a uniform resolution map of the seafloor topography

  • Geodesy

    Geodesy is the science of the Earth's shape and size. Altimetry makes it possible to compute Mean Sea Surface; such a surface includes the geoid, i.e. the shape of the sea surface, assuming a complete absence of any perturbing forces (tides, winds, currents, etc.).

  • Other Geophysical applications

    Altimetry also makes it possible to start on other geophysical applications : tectonic plate motions, poles motions, crustal motions, International Reference System, Earth's Centre of gravity... Doris, precise orbit determination and positioning onboard altimetry satellites, becomes a real space surveyor to develop geodesy and geophysics applications.

  • Tsunamis

    Tsunamis are waves triggered by the vertical deformation of the ocean bottom, caused by submarine earthquakes or landslides.Theoretically, sea level anomalies observed by altimetry should reflect these waves. However, observation is difficult, since the additional height is one of the signals of ocean variability.

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