Static and Dynamic Performance of the RBRargo3 CTD

The static and dynamic performances of the RBRargo3 are investigated using a combination of laboratorybased and in situ datasets from floats deployed as part of an Argo pilot program. Temperature and pressure measurements compare well to co-located reference data acquired from shipboard CTDs. Static accuracy of salinity measurements is significantly improved using 1) a time lag for temperature, 2) a quadratic pressure dependence, and 3) a unit-based calibration for each RBRargo3 over its full pressure range. Long-term deployments show no significant drift in the RBRargo3 accuracy. The dynamic response of the RBRargo3 demonstrates the presence of two different adjustment time scales: a longterm adjustment O(120) s, driven by the temperature difference between the interior of the conductivity cell and the water, and a short-term adjustment O(5-10) s, associated to the initial exchange of heat between the water and the inner ceramic. Corrections for these effects, including dependence on profiling speed, are developed.

Automated summary

In this study, the static and dynamic performances of the RBRargo3 instrument were examined using laboratory-based and in situ datasets. The results show that temperature and pressure measurements compare well with reference data, and the static accuracy of salinity measurements is significantly improved with certain calibration methods. Long-term deployments also indicate no significant drift in accuracy. Additionally, the dynamic response of the instrument revealed the presence of two adjustment time scales, and corrections were developed for these effects.