High quality oxygen measurements from profiling floats:: A promising new technique

Two state-of-the-art profiling floats were equipped with novel optode-based oceanographic oxygen sensors, Both floats were simultaneously deployed in the central Labrador Sea gyre on 7 September 2003. They drift at a depth of 800 db and perform weekly profiles of temperature, salinity, and oxygen in the upper 2000 m of the water column. The initial results from the first 6 months of operation are presented. Data are compared with a small hydrographic oxygen survey of the deployment site. They are further examined for measurement quality, in including precision, accuracy, and drift aspects. The first 28 profiles obtained are of high quality and show no detectable sensor drift. A method of long-term drift control is described and a few suggestions for the operation protocol are provided.