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Earth Observations from Space: The First 50 Years of Scientific Achievements
FIGURE 11.1 View of Earth’s geoid from the GRACE mission yields deep structures. Using an ellipsoid to approximate the bulk of the Earth’s shape and departures from the ellipsoid are represented by the geoid elevation above or below the ellipsoid. The geoid can be as low as 106 m (350 f) below the ellipsoid or as high as 85 m (280 f) above. SOURCE: NASA/Deutsches Zentrum für Luft-und Raumfahrt (DLR).
FIGURE 11.2 Earth’s gravity anomaly from the GRACE mission yields smaller-scale structures. Standard gravity is defined as the value of gravity for a perfectly smooth “idealized” Earth, and the gravity anomaly (expressed in units of milliGals [mGal]) is a measure of how actual gravity deviates from this standard. SOURCE: NASA/DLR.