OOPC 12th Session UNESCO Argo-Oxygen Program Overview White paper produced by writing team lead by Nicolas Gruber Scientific justification for measuring sub- seasonal to decadal O 2 changes: –O 2 is rather sensitive to changes in circulation and biology –Subsurface O 2 changes are an indication of oceanic export production –Important to understand ocean O 2 outgassing for interpretation of the atmospheric O 2 record New sensor technology means drift and accuracy can be within the required limits

OOPC 12th Session UNESCO Argo-Oxygen Program update White paper presented to the AST-8 in March –Well received & AST supported Dr Gruber’s propsal for a coordinated pilot study –AST concerned over the effect on battery life, float failure rates, cost, and implications for current legal agreements For the pilot study, it was agreed that SIC would oversee the project for the next phase and that Dr Gruber will continue to lead the Argo-Oxygen team.

OOPC 12th Session UNESCO Technical issues Choice of floats (ARGOS vs Iridium) –CTD pumps, data upload rates Sensors types (IDO vs Optode) –Accuracy, drift Adding O 2 reduces battery life by 10-30% (can be compensated by more efficient Seabird CTD pump) Increased cost (inc. sensors, data transfer) is 20-30%, and around 40% when reduced float lifetime is taken into account

OOPC 12th Session UNESCO Implementation Phase Deploy around 100 floats in a concentrated area of scientific interest (i.e. Nth Atlantic, Nth Pacific) Cost for 2 years of floats ~$2.5M + ship time + regular Winkler titrations from ships to validate float obs Integrate pilot study with i.e. biogechemical modelling studies to estimate export production