What term describes the differences between observed gravity and the values predicted by a gravity model?

What term describes the differences between observed gravity and the values predicted by a gravity model?

• A. Gravity anomaly
• B. Gravity gradient
• C. Vertical deflection
• D. Geoid height

Answer: (A)

Gravity anomaly is the difference between what you measure for gravity and what a gravity model predicts at that location. This discrepancy reflects local mass variations in the crust and upper mantle, topography, and similar features that the reference gravity field doesn’t perfectly capture. A positive anomaly means the observed gravity is stronger than the model predicts, while a negative one means it’s weaker. In practice, these differences are often analyzed after applying corrections (like Bouguer or free-air) to separate different components, but the fundamental idea is the mismatch between observed gravity and the modeled value. The other terms describe different ideas: gravity gradient is how gravity changes in space, vertical deflection is the angular tilt of the vertical, and geoid height is the vertical separation between the geoid and the reference ellipsoid.

Gravity anomaly is the difference between what you measure for gravity and what a gravity model predicts at that location. This discrepancy reflects local mass variations in the crust and upper mantle, topography, and similar features that the reference gravity field doesn’t perfectly capture. A positive anomaly means the observed gravity is stronger than the model predicts, while a negative one means it’s weaker. In practice, these differences are often analyzed after applying corrections (like Bouguer or free-air) to separate different components, but the fundamental idea is the mismatch between observed gravity and the modeled value. The other terms describe different ideas: gravity gradient is how gravity changes in space, vertical deflection is the angular tilt of the vertical, and geoid height is the vertical separation between the geoid and the reference ellipsoid.