Contrasting views of the annual carbon cycle observed with SOCCOM profiling floats in the Pacific and the Atlantic sectors of the Southern Ocean: A glimpse of future views provided by global observing systems

The Southern Ocean Carbon and Climate, Observations and Modeling program (SOCCOM) is building an array of profiling floats equipped with biogeochemical sensors. These profiling floats, with 6 year lifetimes, are designed to extend the decadal-scale observations of the GO-SHIP repeat hydrography program into the seasonal and interannual domain. Profiling floats that are equipped with oxygen, nitrate, pH, and biooptical sensors are deployed from GO-SHIP sections, or from ships of opportunity that make GO-SHIP quality observations, to ensure the consistency of the float observations with the long-term climatology. Observations are made from near 2000 m to the surface at 10 day intervals. SOCCOM has deployed arrays of these floats along the P16S line at 150°W in the Pacific and along the A12 line at 0° in the Atlantic. Data from the floats are quality controlled and made available in real time at http://soccom.princeton.edu. The floats are equipped with ice avoidance software to enable operations under ice and floats have been deployed as far south at 68°. At the time of the meeting, nearly two years of data will be available from the Pacific and one year of data in the Atlantic. Dissolved inorganic carbon concentrations are derived from the observed pH and estimates of total alkalinity that are estimated from global climatologies. Initial assessments of air-sea gas exchange and net community production derived from the annual changes in dissolved inorganic carbon, oxygen, and nitrate concentrations along these sections, which were developed using 1D mixed layer models, will be presented. The contrasting views from these floats provide a suggestion of the future capabilities of basin scale observing systems based on profiling floats with biogeochemical sensors.