Static and dynamic performance of the RBRargo3 CTD

Abstract

The static and dynamic performances of the RBRargo3 are investigated using a combination of lab-based and in situ datasets from floats deployed as part of an Argo pilot program. Temperature and pressure measurements compare well to colocated 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 timescales: a long-term 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 by the initial exchange of heat between the water and the inner ceramic. Corrections for these effects, including dependence on profiling speed are developed.