Absolute Gravimetry

Absolute gravimetry is the measurement of the Earth’s gravitational acceleration (g) at a specific location using instruments that determine gravity in absolute units (m/s²), without requiring calibration against another gravimeter. Modern absolute gravimeters typically measure the free-fall motion of a test mass in a vacuum using laser interferometry to determine its acceleration with very high precision.

In geodesy, absolute gravimetry provides fundamental observations for the realization of gravity reference networks, the determination of the geoid, and the monitoring of temporal gravity changes caused by mass redistribution in the hydrosphere, cryosphere, atmosphere, and solid Earth. It is essential for calibrating relative gravimeters and for ensuring the long-term stability and consistency of national and global gravity field measurements.