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Effective resolution and drift of Paroscientific pressure sensors derived from long‐term seafloor measurements

Starting with the installation of the NOAA tsunami early warning system DART in 1983, the Paroscientific Digiquarz® Broadband Depth Sensor has been deployed for long‐term ocean bottom pressure measurements in numerous marine investigations. The sensor turned out to be very reliable with a good signal repeatability within a broad measuring range and high resolution. However, up to now its long‐term drift, noise level, and effective resolution under in situ conditions at the seafloor are only known from a few published studies and for a few sensors. In this study we analyze 118 long‐term seafloor pressure time series (longer than 2 months and up to a maximum time period of 9 years) to investigate effective resolution and long‐term drift under in situ conditions. The data are from DART, IFM‐GEOMAR, LOLEM, and CORK stations. The noise level of the data and therefore the mean sensor resolution are lower than an upper threshold of 20.7 Pa (corresponding to 2.07 mm equivalent water level) for stations installed directly on the seafloor. The noise level of CORK sensors is much larger, with a median value of 127 Pa. Long‐term sensor drift is assumed to be composed of an initial exponential part and a subsequent linear drift. In situ mean drift is −0.88 ± 0.73 kPa/a, determined from all available data with a slight increase of drift with deployment depth. For the first time, we are able to quantify effective pressure resolution and drift of the widely used Paroscientific pressure gauges under in situ conditions. Our results provide important constrains for the interpretation of seafloor pressure records. However, in situ self‐calibration procedures for the Paroscientific sensors are still needed in order to benefit from high effective resolution and long‐term stability and also to increase accuracy especially for the monitoring of geodynamic processes at the seafloor.