Land-Sea-Air

The accuracy of each individual measurement

Resolution: How closely can we sample the gravity field

Reliability

Corrections related to how accurate we know the height and location

Corrections related to how to measure

The x-axis represents the inaccuracy of the data

The x-axis represents the accuracy of the data

The y-axis represents the accuracy of the data

The x-axis represents the resolution of the data

Land/Seabed are the most accurate / high resolution

Survey specification generally limits “drift” to 0.03 mGal.

Survey specification generally limits “drift” to 1 mGal.

It is still conventional to treat residual loop mis-closure as linear drift.

Instrument Scintrex A10 Accuracy 0.01 mGal

Instrument Scintrex A12 Accuracy 1 mGal

The reference system for land gravity IGSN71 gravity reference network

The reference system for land gravity Potsdam system reference network

Lacoste & Romberg model G/D

Scintrex CG- 5 Autograv

Geometrics 25-10

Absolute: measure the time of falling weights in a media, accuracy (0.01 mGal) Relative:

Absolute: work by directly measuring the acceleration of a mass during free fall in a vacuum, when the accelerometer is rigidly attached to the ground (0.01 mGal) Relative: Measure extension of a spring, portable, robust more precise (0.005 mGal) They are used in gravity surveys over large areas for establishing the figure of the geoid over those areas.