Vision of a Clock-Based Network for Absolute Sea Level Monitoring

Global sea level shows an increasing trend for several decades driven mainly by climate change. Absolute Sea Level (ASL) changes can only be extracted from Relative Sea Level (RSL) measurements with proper reduction of vertical land movements of the bench marks. Atomic clocks at those tide gauges can potentially provide the absolute, near real-time physical height change. High-performance clocks with an uncertainty of 10⁻¹⁸ enable a height measurement with 1 cm accuracy. As RSL is related to regional tidal datums, one has to account for the local variations to obtain a globally consistent measurement of ASL. Hence, by incorporating land motion from clock observations, one can establish a consistent and uniform reference datum for assessing geoid-based absolute sea level changes worldwide.