The Self Calibrating Pressure Recorder (SCPR) is used for semi-permanent, continuous pressure recording at the seafloor.
A gimbaled platform holds a piston gauge calibrator which can be periodically connected to recording pressure gauges. Normally the gauges record ambient sea water pressure to detect changes in the height of the seafloor.
To distinguish between gauge drift and real height change, the gauges must be periodically calibrated. This is done with motor-controlled valves that switch the hydraulic inputs to the gauges from the external sea water to an internal piston calibrator. A belt and motor assembly spin the mass mounted to the piston to reduce the effects of friction. The calibrator produces a reference pressure whose stability is a few parts per million.
Typically multi-year SCPR deployments involve dozens of sensors placed over and around an offshore reservoir. Regular acoustic data retrieval is possible via ship or autonomous underwater vehicles (AUVs) with satellite transmission of data directly to the customer.
The SCPR, originally developed at Scripps Institution of Oceanography, is now manufactured and tested at the Quad Geometrics San Diego facilities.
Sasagawa, G.S., and M.A. Zumberge (2013), A self-calibrating pressure recorder for detecting seafloor height changes, IEEE. J. Ocean Eng., 38(3).
Munk, W., R. Revelle, P. Worcester, and M. Zumberge (1990), Strategy for future measurements of very-low-frequency sea-level change, in:Sea-level change, Geophysics Study Committee, National Research Council, National Academy Press, Washington, D.C., 221-228.