Long-term measurements of dissolved oxygen from Argo floats

Stephen C. Riser
School of Oceanography
University of Washington
Seattle, WA 98195 USA

We assess the performance of dissolved oxygen sensors on over 20 profiling floats deployed in Argo. Some of these sensors performed well for nearly 3 years, showing only small values of sensor drift over this time. Several sensors showed only weak drift over times in excess of one year, although there were calibration offsets in the data that appeared immediately after deployment. In other cases, sensors failed within a few profiles of deployment. We have deployed several floats with SeaBird and Aanderaa/Optode sensors mounted side-by-side for comparison; in these cases there are some systematic differences between the measurements but in general the two sensors agree remarkably well. In general it has been sound that, making dissolved oxygen measurements from profiling floats is very promising, although more work is required on sensor integration and development before these techniques can be routinely used in Argo.