Absolute gravity measurements at UK tide gauges

Abstract

Absolute gravity near 3 of the United Kingdom's (UK) core tide gauges was repeatedly measured using an FG5 gravimeter over a period of 3–4 years to determine vertical land movements at those gauges. The absolute gravity sites were established at Newlyn and Aberdeen in 1995 and in Lerwick in 1996. Assuming a height change of 1 mm causes a change in gravity of 0.2 µgal we see vertical land movements of 1.0±1.4 mm/yr at Newlyn, −3.8±1.6 mm/yr at Lerwick and 0.9±3.1 mm/yr at Aberdeen. These land movements are, within the error estimates, in agreement with land movement predicted by a model of post‐glacial rebound/subsidence. To ensure that our absolute gravimeter is giving accurate results it has been regularly intercompared with other absolute gravimeters and was verified to be in agreement at the 2 µgal level.