The PROVOR CTS4: a float network to study ocean biogeochemistry

摘要

For more than 15 years, ARGO floats have been following the same basic 10-day cycle. The float is activated and dives to 1000 metres depth where it drifts for nine days, before descending again to 2000 metres depth. On the tenth day the float rises to the surface while performing a CTD (conductivity, temperature, depth) profile, which is then sent to shore via satellite. The float follows this cycle until its batteries are drained (a float has a life span that ranges from four to seven years). Thus, a network of autonomous floats permanently feeds the ARGO database. Inspired by the early success of the ARGO network, in 2006 a team from the Laboratoire d'Océanographie de Villefranche-sur-Mer (LOV) in France expressed a desire to add biogeochemical sensors to the floats. As a result, in addition to the conventional sensors of pressure, temperature and salinity, a series of optical sensors were installed on a new generation of float, known as the PROVOR CTS3. The sensors included a transmittance sensor for the measurement of opacity, EC03, a sensor which simultaneously measures fluorescence, backscatter and CDOM (dissolved organic material), and an irradiance sensor. Two nutrient sensors (SUNA and ISUS) and a sensor for measuring dissolved oxygen were also added.