Understanding the Ocean Carbon Cycle from Atmospheric Measurements of O 2 and CO 2 Andrew Manning, UEA, UK

Dave Keeling The Keeling Curve

Dave Keeling Ralph Keeling The Keeling Curves

Simplified Global Budgets:  CO 2 = F – O – L Atmosphere-Ocean gas exchange Photosynthesis Respiration Fossil fuel burning Simplified global CO 2 cycle F= fossil fuel carbon emissions O= net oceanic carbon sink L= net land biotic carbon sink + Z Z= net oceanic O 2 source  O 2 = –  F F +  L L  F = average fossil fuel O 2 :CO 2 ratio  L = average land biotic O 2 :CO 2 ratio and O 2 cycles

Quantifying global oceanic and land biotic carbon sinks

Manning, 2001 & IPCC TAR, 2001 Manning & Keeling, Tellus, 2006 & IPCC AR4 draft, 2006 Units: Pg C yr Fossil-fuel emissions:6.3 ± ± 0.4 Atmospheric CO 2 increase:3.2 ± ± 0.1 Net oceanic carbon sink:1.7 ± ± 0.6 Net land biotic carbon sink:1.4 ± ± 0.7  O 2 = –  F F +  L L + Z  CO 2 = F – O – L Quantifying global oceanic and land biotic carbon sinks

APO - Atmospheric Potential Oxygen APO = O 2 +  L CO 2 APO is conservative with respect to land biotic processes So APO variations result only from: - oceanic CO 2 sink (long term) - oceanic O 2 fluxes (short term)

 From atmospheric O 2 (APO) observations and transport model inversion get F O 2 (oceanic O 2 flux). Then calculate k g2 from: F O 2 = k g2 [ pO 2(oc) – pO 2(atm) ]  Use this k g2 with CO 2 observations to derive air-sea CO 2 fluxes with less uncertainty. Wanninkhof and McGillis, GRL, 1999 Gas exchange velocities from APO measurements  Regional quantification of ocean carbon sinks F CO 2 = k g1 [pCO 2(oc) – pCO 2(atm) ] Large uncertainties in k g1  Large uncertainties in calculated air-sea CO 2 fluxes.

Stephens et al., GBC, 1998 Gruber et al., GBC, 2001 Latidudinal distribtion of APO fluxes  Validation and improvement of ocean BGC models

Battle et al., GBC, 2006 Tohjima et al., GRL, 2005

DurbanFelixstowe Felixstowe to Durban Periodicity = 45 days 8 cruises/yr CarboOcean atmospheric O 2 /CO 2 measurements

See poster by Michael Patecki for more info

Atmospheric O 2 /CO 2 measurements in CarboOcean: Michael Patecki, UEA, U.K. Poster: System development and preliminary results of atmospheric O 2 and CO 2 from shipboard measurements in the North Atlantic Ocean. Jost Lavric, LSCE, France Poster: Continuous high accuracy atmospheric O 2 /N 2 and CO 2 measurement – a new automatic station on Cape Farewell, Southern Greenland. Ingrid Luijkx, RuG, The Netherlands Poster: Continuous atmospheric CO 2 and O 2 measurements on the F3 North Sea gas and oil platform. Harro Meijer, RuG, The Netherlands

1) Atlantic O 2 + CO 2 measurements a) CarboOcean, with Michael Patecki Continuous, automated measurements, achieved with: - “Oxzilla” fuel cell O 2 analyser - Siemens NDIR CO 2 analyser - “Blue Box” for calib. gases - 2-stage drying system

Stephens et al. (1998) Gruber et al. (2001) Lack of O 2 observation!

Data and figure courtesy of Y. Tohjima, NIES, Japan Pacific Ocean shipboard flask measurements,

APO interannual variability mol O 2 /yr x ocean models under-estimate observed variability Buitenhuis, Le Quéré, Keeling

Simplified Global Budgets:  CO 2 = F – O – L Atmosphere-Ocean gas exchange Photosynthesis Respiration Fossil fuel burning Simplified global CO 2 and O 2 cycles F= fossil fuel carbon emissions O= net oceanic carbon sink L= net land biotic carbon sink  O 2 = –  F F +  L L  F = average fossil fuel O 2 :CO 2 ratio  L = average land biotic O 2 :CO 2 ratio + Z Z= net oceanic O 2 source

APO - Atmospheric Potential Oxygen (  CO 2 = F – O – L ) x  L +  O 2 = –  F F +  L L + Z  APO Fossil fuel APO loss Oceanic APO loss  O 2 +  L  CO 2 = (  L –  F )F – (  L O – Z) 1) Solve ‘O’ with  APO 2) Solve ‘L’ with  CO 2 - land sink more variable, and have larger CO 2 network - less “noise” in long-term APO trend

Keeling and Garcia, PNAS, 2002.

CarboOcean – observations theme led by UEA - 5 year, 15 million Euro programme quantify net annual air-sea CO 2 fluxes in North Atlantic Ocean (and world ocean) -main objective: to quantify net annual air-sea CO 2 fluxes in North Atlantic Ocean (and world ocean) My contribution: continuous, automated system for measurements of atmospheric O 2 and CO 2 from ships (to complement measurements of dissolved O 2 and CO 2 )

Felixstowe Antwerp Gran Canaria Cape Town Port Elizabeth Durban Felixstowe to Durban Periodicity: Felixstowe is visited every 45 days