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NORTHEAST PACIFIC CARBON PROGRAM

NORTHEAST PACIFIC CARBON PROGRAM Investigating the mechanisms responsible for massive CO 2 drawdown at the subarctic-subtropical gyre Steven Emerson, Paul Quay, Charlie Eriksen , Ricardo Letelier. Carbocean, Dec, 2008.

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NORTHEAST PACIFIC CARBON PROGRAM

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  1. NORTHEAST PACIFIC CARBON PROGRAM Investigating the mechanisms responsible for massive CO2 drawdown at the subarctic-subtropical gyre Steven Emerson, Paul Quay, Charlie Eriksen, Ricardo Letelier Carbocean, Dec, 2008 Ten Year average of SeaWIFS ocean color data (1997-2007)(NASA/MODIS ocean color http://oceancolor.gsfc.nasa.gov

  2. IN SITU MEASUREMENTS OF NET BIOLOGICAL OXYGEN PRODUCTION COLLABORATORS: Roo Nicholson, Charlie Eriksen, Chuck Stump U.W. Meghan Cronin,Chris Sabine, PMEL Mike DeGranpre, U.Montana; Marie Robert IOS, BC, CA Tommy Dickey, HOT Scientists Ten Year average of SeaWIFS ocean color data (1997-2007)(NASA/MODIS ocean color http://oceancolor.gsfc.nasa.gov

  3. GOAL To Determine the Value of Oxygen and Carbon Export form the Ocean Euphotic Zone and the Processes Controlling it X X X X (Laws, 2000, GBC, 14, 1231) (Schlitzer, 2000, Geophys. Mono. 114)

  4. UPPER OCEAN OXYGEN DYNAMICS d[C]/dt = diffusive gas exchange + bubble exchange + diapycnal mixing + isopycnal mixing +biological production

  5. STUDY LOCATIONS AND METHODS The MOSEAN Mooring and Seaglider The Hawaii Ocean Time Series (HOT) 2005-2006 The UW-PMEL Mooring and Seaglider at Stn P (2007 - ) Sensors: CTD-O2-GTD, 10 m Sensors: T, S, O2 Sensors: CTD-O2-GTD, pCO2, pH

  6. Atmosphere &Total Dissolved Gas Pressures in the surface Ocean at HOT & Stn P HOT GTD atmosphere Stn P

  7. Pressure of N2 (pN2) is determined from atmospheric and total dissolved gas pressure, and [O2 ] pN2 = PW,GTD – (PAtm-pH2O)(XAr+XCO2) – pH2O – [O2]/KH,O2 HOT Stn P

  8. Calculation of Net O2 production from O2 and N2 data h(d[O2]/dt) = -Fair-water + dh/dz ([O2,therm –[O2]) + Fpyc + JbioFa-w = Diffusive Exchange + Bubble TransferFa-w = G{[O2,sat] – [O2]} + (Vinj+ VexD0.5α}XO2 G = mass transfer coefficient (Wind Speed)V = Bubble transfer coefficients h = mixed layer depth D= molecular diffusion coef. α = solubility X = atmospheric mole fraction Assume: Vinj= VexDαFpyc = 0 Use N2 to determine V O2 to determine J

  9. Cumulative O2 Production at HOT the important terms in the mass balance Mixed-layer O2 Production = 4.8 ± 2.7 mol m-2 yr-1 (Emerson et al., 2008, GBC)

  10. Oxygen Productivity below the Mixed Layer:T, S, and Oxygen concentration on Sea Glider (Nicholson, Emerson, Eriksen, 2008, L&O 53, 2226 ) NW SW NE SE X Aloha Glider path and mean O2 superaturation  Correlation among: SSH, isopycnal depth, [O2]  NCP (below the m. l.) =0.9 mol C m-2 yr-1

  11. Summary of Biological O2 Production at HOT and Stn P: from mooring and glider measurements Mixed-layer O2 Production = 4.8 ± 2.7 mol m-2 yr-1 (Emerson et al., 2008) Submixed layer Production = 0.9 ± 0.3 (Nicholson et al., 2008) Flux across the thermocline  0.0 – 0.8 mol m-2 yr-1 (Kz = 0.1-1.0 cm2 s-1) Biological O2 Production = 6.1 ± 3.1 mol m-2 yr-1 HOT: Net Biological C Production = 4.2 mol C m-2 yr-1 STN P: Net Biological C Production = 2.3 mol C m-2 yr-1 HOT STA P

  12. CONCLUSION: O2 and Organic C export is at least as great at Hot as it is at Stn P – Satellite Export is uncalibrated! mol C m-2 yr-1 2.3 4.2

  13. The Role of CaCO3 and Organic Matter Production in DIC Change [CO32-] calculated pH and pCO2 at Stn P pH = 8.10, pCO2 = 400 ppm pCO2 pH [CO3] increases by ~25 mol kg-1 in summer  pH = 8.05, pCO2 =350 ppm pCO2 Chris Sabine pH Steve Emerson and Mike deGranpre

  14. Calculating the fraction of the DIC Change that is due to CaCO3 formation and O.M. formation (1) ΔDIC =ΔDIC(om) + ΔDIC(CaCO3) (2) ΔAlk = ΔAlk (om) + ΔAlk(CaCO3) (3) ΔDIC(om) = ΔO2 rDIC:O2 = ΔO2 (-106/154) (4) ΔAlk(om) = ΔO2 rAlk:O2 = ΔO2 (16/154) (5) 2 ΔDIC(CaCO3) = ΔAlk(CaCO3) (6) ΔAlk - ΔDIC = 25 μmol kg-1 Combining these equations gives: ΔDIC (CaCO3) / ΔDIC (om) = 1.4 [CO3] increases by ~25 mol kg-1 in summer (3) RESULTS: O2 AND N2 SUPERSATURATION IN THE MIXEDLAYER

  15. CONCLUSIONS 1. It is possible to determine the major components of the carbon fluxes remotely using presently available in situ sensors 2 . Net Oxygen (Organic Carbon) Production in the subtropical North Pacific is ≥ that in the subarctic Pacific which meaning that models and satellite color predictions are not yet correct. 3. Net Carbon Production HOT (subtropical) NCP = 4.2 mol C m-2 yr-1 Stn P (subarctic) NCP = 5.5 ncp (o.m.) = 2.3 ncp (CaCO3) = 3.2

  16. THE FUTURE (A) A Global distribution of moorings and sensors

  17. THE CHALLENGE

  18. Can We Develop Methods of Determining the Net Annual Biological Carbon Pump Remotely?(Both organic carbon and CaCO3!)

  19. GLOBALGOAL: To Understand the Importance of Biological Carbon Export in Determining the Ocean-Atmosphere Flux of CO2 For Example: There is presently a discrepancy between annual carbon export determined by O2 mass balance and that predicted by satellite color X X X X X 1 3 10 30 Net Carbon Export (mol C m-2 yr-1) Laws et al., 2000

  20. Improve the Calibration of Model-Determined Productivity and Carbon Export X X Models also predict more carbon export in upwelling areas and less in the open ocean (Schlitzer, 1999) X X X X X

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