Cogeoid

In geodesy, the cogeoid is the changed shape and altitude of the geoid when a change in the mass distribution is calculated . This is always the case, for example, when applying a topographical reduction to measured gravity values.

Explanation: If one imagines the surrounding rock masses of the mountain slopes to be removed during a gravity measurement in a valley , then the force of gravity increases because the effect of the upward pulling mass of the terrain is no longer applicable. The gravity potential also increases, and with it all level surfaces shift slightly upwards.

The geoid becomes the cogeoid of the corresponding mass displacement, i.e. the cogeoid of the topographical reduction .

The same happens if one assumes changed densities or a change in depth of the interface between the earth's crust and the earth's mantle , the Mohorovičić discontinuity . Analogously, one could speak of the cogeoid of the Moho change here .

See also

• Weight reduction , indirect effect
• Geoid determination , isostasis

literature

• K.Ledersteger : Astronomical and Physical Geodesy (Earth Measurement) , JEK Volume V, Chapter 4 (Plumb line deviation, Geoid determination) and 11 (Gravity reductions), JBMetzler-Verlag, Stuttgart 1968