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4 New space techniques for gravity field mapping
4.1 The idea
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A significant improvement can only be expected from new satellite techniques.
However, any satellite technique for gravity field mapping has one pitfall, which
is illustrated in figure 4. The bottom panel shows the gravity signal at the Earth s
surface. It mainly reflects the topography, thus containing many short-wavelength
features. The top panel shows what signal is left at an altitude of 250 km.
Obviously, small scale features are highly damped, and only the dominant large
scale features are still visible. Therefore, altitude acts as a low pass filter, and the
gravity signal of small scale mass inhomogeneities can hardly be seen at satellite
altitude.
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0 60 120 100 240 300 360
Longitude
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Gravity anomalies at 250km altitude
Figure 4: The attenuation effect
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Gravity anomalies at 0km altitude
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Longitude
