Meaning
A computational correction technique used to account for the lag in a sensor’s output during ascent and descent cycles ensures high accuracy in profiling instruments. Applying pressure hysteresis modeling correction allows oceanographers to obtain consistent measurements of temperature and salinity regardless of whether the sensor is moving upward or downward through the water column. The method utilizes historical calibration data to build a predictive mathematical model of the sensor’s physical lag.
This step is necessary because the physical housing of the sensor does not compress and expand instantly.
Accuracy Guarantee
Distribution agreements for oceanographic profiling floats often specify the maximum allowable hysteresis error. To satisfy these performance requirements, manufacturers must integrate pressure hysteresis modeling into the sensor’s onboard firmware. The sensor must deliver real-time data that fall within the specified error bounds during rapid profiling runs.
When the sensor fails to meet these bounds, the distributor must provide firmware updates or recalibrate the unit. This proactive approach ensures that the end-user receives high-quality data immediately after the instruments are deployed.
Supplier Warranty
Deficiencies in the pressure response can lead to the rejection of entire batches of instruments. Contracts often stipulate that pressure hysteresis modeling must be validated by an independent testing facility before shipment. If the testing reveals that the sensor’s lag exceeds the allowable threshold, the supplier is obligated to replace the affected components at their own expense.
This clause prevents the delivery of sensors with substandard piezo-resistive elements.
Data Validation
Post-cruise processing of the collected data uses these models to refine the final records. When the pressure cycles are asymmetric, the models are adjusted to align the upcast and downcast profiles. This adjustment is verified by comparing the corrected values against known deep-water standards.
