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Physical Reference Surfaces
The most important physical reference surfaces are determined by the Earth gravity field. They reflect the irregular distribution of masses on and inside the Earth. The Earth gravity field also affects satellite orbits and is important for the surveying of the Earth. Heights, for example, should refer to a unique global height reference surface.

Only with precise knowledge of the gravity field, can point positions and heights be determined with the utmost accuracy. DGFI investigates high resolutions and improved representations of the Earth gravity field and contributes to the evaluation of new and upcoming gravity field missions (CHAMP, GRACE and GOCE).

Mean sea level change (mm/year) for the period 1993-2001, derived from observations of the TOPEX/Poseidon satellite altimeter mission
See also MPEG-movie showing TOPEX/Poseidon derived sea level anomalies in the Pacific Ocean (~60 MB !!)
Sea level adjusts itself to the gravity field. It is, however, also affected by temperature, air pressure and ocean circulations. Surveying the sea level and analysing temporal sea level changes gives information on general processes within the system Earth

By satellite altimetry sea surface heights can be obtained with centimeter precision. DGFI also determines temporal sea level changes, compares them with tide gauge records and investigates their influence on the gravity field and the rotation of the Earth.
See projects B1, B2, B3 und B4.
wb 02/2002 comments