Deepwater pressure measurements with the highest level of stability are critical for climate, global ocean circulation, and geophysical process studies. The RBRquartz³ BPR|zero is a special version of the RBRquartz³ BPR (bottom pressure recorder) implementing an internal barometer and switching valve. The novel AzeroA technique is used to provide in-situ reference measurements to correct for long term drift in the Paroscientific Digiquartz® pressure gauge.
The AzeroA technique is used to assess drift in the quartz pressure gauge. This is done by periodically switching the applied pressure that the gauge measures from seawater to the atmospheric conditions inside the housing. The drift in quartz sensors is proportional to the full-scale rating, so a reference barometer – with hundreds of times less drift that the marine gauge – is used to determine the behaviour of the marine pressure measurements. Employing the AzeroA correction will typically reduce the bottom pressure drift to less than 1cm/year at 7000dbar. The RBRquartz³ BPR|zero comes with a high-accuracy temperature sensor and may be supplied with a second (redundant) quartz pressure gauge and, optionally, a triaxial quartz accelerometer.
This instrument is intended for deepwater, long-term deployments where high stability and resolution of absolute pressure measurements are critical. Combined with the RBRfermata external battery canister, the RBRquartz³ BPR|zero can sample continuously at 1Hz for 600 days or every 10s for more than eight years. Despite being located on the seafloor, the high resolution (10ppb) quartz pressure sensor is able to detect 700µm changes in surface water level from 7,000m below the surface.
Researchers at the University of Washington Applied Physics Lab have been using RBRquartz³ BPR|zero control and logging components for bottom pressure measurements on a real-time cabled array for geophysical studies. Scientists at the French National Centre for Scientific Research (CNRS) will start using the RBRquartz³ BPR|zero to detect small and slow vertical submarine movements associated with the Mayotte volcano activity.