1. Joos, Plattner, Stocker, Körtzinger, and Wallace (2003). EOS 84, 197-204. WP10 The motivation

2. Electrochemical sensor (Seabird SBE 43/IDO) Optode sensor (Aanderaa 3830) Measurement range: 120% of surface saturation Initial accuracy: 2% of saturation Response time: 6 s (e-folding time) Measurement range: 0-120% of surface saturation (0-500 µM) Precision: <1 µM (0.4%) Initial accuracy: 8 µM or 5% (whichever is greater) Response time: 25 s (e-folding time) Principle: Life time based dynamic fluorescence quenching Principle: Clark-type polarographic membrane sensor UW floats (S. Riser) WP10 The technological situation

3. Körtzinger et al. (2005). High-quality oxygen measurements from profiling floats: A promising new technique. J. Atm. Ocean. Techn. 22, 302-308. Tengberg, Körtzinger et al. (2006). Evaluation of a life time based optode to measure oxygen in aquatic systems. Limnol. Oceanogr. Methods 4, 7-17. Drift check possible through air measurements High long-term stability O 2 = 295.0 ± 0.7 µmol/L WP10 The technological situation

4. Körtzinger et al. (2004). The ocean takes a deep breath. Science, 306, 1337. quasi-stationary float WP10 The science showcase

5. PROVOR-DOPROVOR-CarboOcean Oxygen sensor PIC sensor March 2007: Delivery of prototype 2 floats from MARTEC company Spring 2007: Testing of floats (vibration, tank, basin) at IFREMER Spring/summer 2007: Sea trials of floats February 2009: field study with deployment of 2 floats (77 and 90 profiles, resp.) November 2006: Delivery of 2 prototype floats from MARTEC company Nov./Dec. 2006: Testing of floats (vibration, tank, basin) at IFREMER February 2007: Deployment during R/V Poseidon Cruise 348 by IFM-GEOMAR north of the Cape Verde archipelago February 2008: field study with deployment of 4 floats (all still active in Oct. 2009) WP10 The technological development

6. PROVOR CTS3 DO PROVCARBON  Final proof-of-concept field experiment using 6 newly developed oxygen floats is successfully running since Feb. 2008  All four PROVOR CTS3 DO float still active after 73-83 profiles  PROVCARBON float stopped after 77 and 90 profiles, resp.  Evaluation of field experiment data ongoing WP10 The field experiment

7. Oxygen time-series  Example: 90 profiles by float WMO #6900632 showing upwelling dynamics off Mauritania active coastal upwelling of low- oxygen waters Sub-surface respiration of organic matter produced in upwelled waters WP10 The scientific potential of an ARGO O 2 observatory

8. Estimation of the wind speed dependence of the gas transfer coefficient (k 660 ) from three years of data in the Labrador Sea convection region Kihm and Körtzinger, in prep. WP10 The scientific potential of an ARGO O 2 observatory

9. Estimation of sub-surface oxygen utilization rates from three years of data in the Labrador Sea convection region Kihm and Körtzinger, in prep. 2003 2004 2005 WP10 The scientific potential of an ARGO O 2 observatory

10. Keeling, Körtzinger, and Gruber (2010). Ocean deoxygenation in a warming World. Annual Review of Marine Science. 2, in press. WP10 The emerging global picture of O 2 trends

11. The latest OMZ trends...

12. Model vs. observations: A16N Simulated and observed decadal variability are of similar order Internal variability of a specific year is up to 20 μmol/kg Observed O 2 -decrease from 1993 and 2003 is 30 μmol/kg Simulated internal varia- bility is up to 45 μmol/kg Impact of the Mt. Pinatubo eruption is negligible Johnson et al. (2007) Introduction Methods Results Caveats/closing thoughts The present ocean The future ocean Long-term changes Frölicher et al. (2009, GBC)

13. Large local O 2 -decrease in thermocline of the North Pacific and the Southern Ocean (due to reduced air-sea gas exchange and reduced ventilation, partly compensated by biological processes) O 2 -decrease in deep North Atlantic (more efficient PO 4 utilization due to lower ventilation) O 2 -increase in tropical thermocline (large decrea- se in export production, possibly reduction in water mass ages) Regional maximum O 2 decrease/increase Depth Frölicher et al. (2009, GBC) Introduction Methods Results Caveats/closing thoughts The present ocean The future ocean Long-term changes

14. Global decrease in dissolved oxygen Total O 2 content is projected to decrease by 5.9 Pmol (2.6%) by year 2100. Solubility-driven changes are responsible for at least 50% of the total decrease. Additional O 2 loss resulting from change in ocean circulation and biology Frölicher et al. (2009, GBC) solubility-driven stratficiation Introduction Methods Results Caveats/closing thoughts The present ocean The future ocean Long-term changes

15. Johnson, K.S., W.M. Berelson, E.S. Boss, Z. Chase, H. Claustre, S.R. Emerson, N. Gruber, A. Körtzinger, M.J. Perry, and S.C. Riser (2009). Observing biogeochemical cycles at global scales with profiling floats and gliders: prospects for a global array, Oceanography, 22, 217-225. WP10 The BGC community is starting to embrace ARGO