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Sasagawa, GS, Zumberge MA, Cook MJ.  2018.  Laboratory simulation and measurement of instrument drift in quartz-resonant pressure gauges. Ieee Access. 6:57334-57340.   10.1109/access.2018.2873479   AbstractWebsite

Seafloor pressure gauges are used in marine geodesy to detect vertical displacement of the seafloor. Instrumental gauge drift is often larger than the sought after geophysical and oceanographic signals. We performed a 12 month laboratory test on two new methods that aim to reduce pressure gauge drift in Paroscientific Digiquartz and other pressure transducers. In one method, a reference quartz oscillator (RQO) is installed adjacent to but isolated from the Bourdon tube whose stress is measured by a vibrating quartz force transducer. In another method, the pressure gauge is periodically connected to accurately measured atmospheric pressure as a reference to allow drift calculation. We found that the RQO is not a good predictor of gauge drift. However, determining drift by periodic exposure to atmospheric pressure is effective. These drift estimates were compared to estimates determined with an absolute piston gauge calibrator; the average difference between drift rates of the two methods is 0.00 +/- 0.05 kPa/year. Finally, we tested the stability of the quartz clocks used in the Paroscientific electronics and found that they are not a significant contributor to drift.

Sasagawa, G, Zumberge M, Eiken O.  2008.  Long-term seafloor tidal gravity and pressure observations in the North Sea: Testing and validation of a theoretical tidal model. Geophysics. 73:WA143-WA148.   10.1190/1.2976778   AbstractWebsite

Seafloor gravity and pressure measurements for 4D reservoir monitoring require precise models of the time-varying tidal signals. Current seafloor instrumentation can resolve 0.003 mGal in time-lapse gravity differences and 0.05 kPa (5 mm) in pressure. To verify model accuracy, a seafloor gravimeter and pressure gauge were operated continuously for 446 days next to the Troll A gas platform in the North Sea (60.64227 degrees north, 3.72417 degrees east) at a depth of 303 m. The seafloor gravity and pressure time series were filtered and corrected with estimates from the tidal model, which predicts the solid earth tide, ocean loading, and direct gravitational attraction of the varying water level. The rms difference between the observed tidal gravity signal and the prediction is about 0.0013 mGal during periods when there are no surface storms. A slight difference is observed for the direct attraction of the water overhead as computed from the tidal prediction versus that computed from direct seafloor pressure measurements when the entire 446-day record is analyzed; it shows an rms difference of 0.708 kPa, equivalent to 7 cm of water-height variation, yielding a gravity effect of 0.003 mGal. We conclude that existing theoretical tide models in combination with in situ pressure records are sufficiently precise for correcting time-lapse gravity observations.