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The vulnerable ocean: Decadal changes in the ocean carbon and oxygen cycles

The vulnerable ocean: Decadal changes in the ocean carbon and oxygen cycles. Nicolas Gruber Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Switzerland.

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The vulnerable ocean: Decadal changes in the ocean carbon and oxygen cycles

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  1. The vulnerable ocean: Decadal changes in the ocean carbon and oxygen cycles Nicolas Gruber Environmental Physics, Institute of Biogeochemistry and Pollutant Dynamics, ETH Zürich, Switzerland Holger Brix1, Curtis Deutsch2, Scott C. Doney3, Arne Koertzinger4, Doug W. R. Wallace4, and Rik Wanninkhof5 (1) IGPP, UCLA, Los Angeles, USA; (2) Univ. of Washington, Seattle, USA; (3) WHOI, Woods Hole, USA; (4) Leibniz Inst. for Marine Sciences, GER; (5) NOAA AOML, Miami, USA.

  2. 1955-1998: Rate of 3.3x1021 J yr-1 = 0.2 W m-2 = 0.1 PW

  3. AAIW MED SPMW LAB NADW AOU = [O2sat] - [O2] APPARENT OXYGEN UTILIZATION STMW SPMW AAIW MED LAB NADW

  4. AOU CHANGES 2003-1993

  5. Expected change from anthropogenic CO2: max 0-8 mmol/kg AOU AND DIC CHANGES 2003-1993

  6. IMBER-SOLAS CO2/CLIVAR Repeat Hydrography Program status ~2005

  7. ARGO: The next generation observing system A global array of profiling floats that measure the temperature and salinity of the upper 2000 m on a ~10 day repeat cycle.

  8. How to get oxygen on ARGO floats: Promising oxygen sensors Electrochemical sensor (Seabird SBE 43/IDO) Optode sensor (Aanderaa 3830) Principle: Clark-type polarographic membrane sensor Principle: Life time based dynamic fluorescence quenching 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 (63% e-folding time) Measurement range: 120% of surface saturation Initial accuracy: 2% of saturation Response time: 6 s (e-folding time) UW floats (S. Riser)

  9. Summary & Outlook • Oxygen concentrations in the thermocline of the North Atlantic have decreased substantially over the last decade, accompanied by a faster than expected increase in DIC. • Most of these changes are likely due to a reduction in the circulation rate of thermocline waters, possibly related to the predominantly positive phase of NAO during the 1990s. • The records are too short to attribute these changes to anthropogenic climate change or to natural variability. • Oxygen is a very sensitive tracer for studying and understanding the response of ocean biogeochemistry to climate variability and global climate change.

  10. The End.

  11. Fundamentals σθ 26.8 σθ 26.4 (σθ ) Apparent Oxygen Utilization AOU = O2sat -O2 (σθ) ΔO2 = ΔO2sat - ΔAOU

  12. DIC CHANGES 2003-1993

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