Impact of circulation on export production, dissolved organic matter, and dissolved oxygen in the ocean: Results from Phase II of the Ocean Carbon‐cycle Model Intercomparison Project (OCMIP‐2)

[1] Results are presented of export production, dissolved organic matter (DOM) and dissolved oxygen simulated by 12 global ocean models participating in the second phase of the Ocean Carbon-cycle Model Intercomparison Project. A common, simple biogeochemical model is utilized in different coarse-resolution ocean circulation models. The model mean (±1σ) downward flux of organic matter across 75 m depth is 17 ± 6 Pg C yr−1. Model means of globally averaged particle export, the fraction of total export in dissolved form, surface semilabile dissolved organic carbon (DOC), and seasonal net outgassing (SNO) of oxygen are in good agreement with observation-based estimates, but particle export and surface DOC are too high in the tropics. There is a high sensitivity of the results to circulation, as evidenced by (1) the correlation of surface DOC and export with circulation metrics, including chlorofluorocarbon inventory and deep-ocean radiocarbon, (2) very large intermodel differences in Southern Ocean export, and (3) greater export production, fraction of export as DOM, and SNO in models with explicit mixed layer physics. However, deep-ocean oxygen, which varies widely among the models, is poorly correlated with other model indices. Cross-model means of several biogeochemical metrics show better agreement with observation-based estimates when restricted to those models that best simulate deep-ocean radiocarbon. Overall, the results emphasize the importance of physical processes in marine biogeochemical modeling and suggest that the development of circulation models can be accelerated by evaluating them with marine biogeochemical metrics.

[1]  P. Quay,et al.  The total organic carbon export rate based on13C and12C of DIC budgets in the equatorial Pacific region , 1997 .

[2]  J. Sarmiento,et al.  Three‐dimensional simulations of the impact of Southern Ocean nutrient depletion on atmospheric CO2 and ocean chemistry , 1991 .

[3]  Kitack Lee Global net community production estimated from the annual cycle of surface water total dissolved inorganic carbon , 2001 .

[4]  Yasuhiro Yamanaka,et al.  Role of dissolved organic matter in the marine biogeochemical cycle: Studies using an ocean biogeochemical general circulation model , 1997 .

[5]  K. Lindsay,et al.  Inverse estimates of anthropogenic CO2 uptake, transport, and storage by the ocean , 2006 .

[6]  J. Saltzman,et al.  Zooplankton ecology in the eastern tropical Pacific oxygen minimum zone above a seamount: 1. General trends , 1997 .

[7]  E. Maier‐Reimer,et al.  Ocean-circulation model of the carbon cycle , 1990 .

[8]  Dennis A. Hansell,et al.  Deep-ocean gradients in the concentration of dissolved organic carbon , 1998, Nature.

[9]  S. Doney,et al.  A modeling study of the seasonal oxygen budget of the global ocean , 2007 .

[10]  Dennis A. Hansell,et al.  Global distribution and dynamics of colored dissolved and detrital organic materials , 2002 .

[11]  John F. B. Mitchell,et al.  The simulation of SST, sea ice extents and ocean heat transports in a version of the Hadley Centre coupled model without flux adjustments , 2000 .

[12]  C. H. Coleman,et al.  The distribution of colloidal and dissolved organic carbon in the Gulf of Mexico , 1994 .

[13]  E. Maier‐Reimer,et al.  Nutrient trapping in the equatorial Pacific: The ocean circulation solution , 1999 .

[14]  L. A. Anderson,et al.  Global ocean phosphate and oxygen simulations , 1995 .

[15]  J. Toggweiler,et al.  Downward transport and fate of organic matter in the ocean: Simulations with a general circulation model , 1992 .

[16]  Scott C. Doney,et al.  Evaluation of ocean carbon cycle models with data‐based metrics , 2004 .

[17]  D. E. Harrison,et al.  An ecosystem model with iron limitation of primary production in the equatorial Pacific at 140°W , 1997 .

[18]  Dennis A. Hansell Chapter 15 – DOC in the Global Ocean Carbon Cycle , 2002 .

[19]  Reiner Schlitzer,et al.  Carbon export fluxes in the Southern Ocean: results from inverse modeling and comparison with satellite based estimates , 2002 .

[20]  J. Toggweiler,et al.  Mediterranean nutrient balance and episodes of anoxia , 1988 .

[21]  Dennis A. Hansell,et al.  Organic carbon and apparent oxygen utilization in the western South Pacific and the central Indian Oceans , 2000 .

[22]  M. Carr Estimation of potential productivity in Eastern Boundary Currents using remote sensing , 2001 .

[23]  S. Gorshkov,et al.  World ocean atlas , 1976 .

[24]  E. Maier‐Reimer,et al.  Geochemical cycles in an Ocean General Circulation Model , 1993 .

[25]  Hugues Goosse,et al.  Importance of ice-ocean interactions for the global ocean circulation: A model study , 1999 .

[26]  Robert R. Bidigare,et al.  Seasonal patterns of ocean biogeochemistry at the U.S. JGOFS Bermuda Atlantic time-series study site , 1994 .

[27]  H. Garcia,et al.  On the Global Oxygen Anomaly and Air-Sea Flux , 2001 .

[28]  P. Gent,et al.  Isopycnal mixing in ocean circulation models , 1990 .

[29]  R. Keeling,et al.  Mean annual cycle of the air‐sea oxygen flux: A global view , 2000 .

[30]  Scott C. Doney,et al.  Seasonal variations in the atmospheric O2/N2 ratio in relation to the kinetics of air‐sea gas exchange , 1998 .

[31]  Richard A. Krishfield,et al.  Factors controlling the flux of organic carbon to the bathypelagic zone of the ocean , 2002 .

[32]  David C. Lowe,et al.  Variability in the O2/N2 ratio of southern hemisphere air, 1991–1994: Implications for the carbon cycle , 1996 .

[33]  J. Sarmiento,et al.  Empirical and mechanistic models for the particle export ratio , 2005 .

[34]  Daniele Iudicone,et al.  Mixed layer depth over the global ocean: An examination of profile data and a profile-based climatology , 2004 .

[35]  M. Follows,et al.  The Ekman transfer of nutrients and maintenance of new production over the North Atlantic , 1998 .

[36]  Dennis A. Hansell,et al.  Marine dissolved organic matter and the carbon cycle , 2001 .

[37]  Thomas F. Stocker,et al.  A Zonally Averaged, Coupled Ocean-Atmosphere Model for Paleoclimate Studies , 1992 .

[38]  K. Lindsay,et al.  Global Ocean Carbon Cycle Modeling , 2003 .

[39]  David M. Karl,et al.  VERTEX: carbon cycling in the northeast Pacific , 1987 .

[40]  W. J. Jenkins,et al.  Seasonal oxygen cycling and primary production in the Sargasso Sea , 1985 .

[41]  G. Plattner,et al.  Decoupling marine export production from new production , 2005 .

[42]  Walker O. Smith,et al.  Temperature effects on export production in the open ocean , 2000 .

[43]  Taro Takahashi,et al.  Sources and flow patterns of deep-ocean waters as deduced from potential temperature, salinity, and initial phosphate concentration , 1985 .

[44]  W. Broecker,et al.  Isotopic versus micrometeorologic ocean CO2 fluxes: A serious conflict , 1986 .

[45]  J. Turner,et al.  A one‐dimensional model of the seasonal thermocline II. The general theory and its consequences , 1967 .

[46]  S. Doney Major challenges confronting marine biogeochemical modeling , 1999 .

[47]  P. Quay Was a carbon balance measured in the equatorial pacific , 1987 .

[48]  K. Lindsay,et al.  Inverse estimates of the oceanic sources and sinks of natural CO2 and the implied oceanic carbon transport , 2007 .

[49]  M. Follows,et al.  Possible overestimation of shallow‐depth calcium carbonate dissolution in the ocean , 2006 .

[50]  A. Hirst,et al.  Climate change feedback on the future oceanic CO2 uptake , 1999 .

[51]  H. Zwally,et al.  Antarctic Sea Ice, 1973-1976: Satellite Passive-Microwave Observations , 1983 .

[52]  E. Maier‐Reimer,et al.  Anthropogenic ocean acidification over the twenty-first century and its impact on calcifying organisms , 2005, Nature.

[53]  D. Karl,et al.  Chapter 6 – Dynamics of DOP , 2002 .

[54]  R. Keeling,et al.  Analysis of the mean annual cycle of the dissolved oxygen anomaly in the World Ocean , 1997 .

[55]  T. R. Anderson,et al.  A one‐dimensional model of dissolved organic carbon cycling in the water column incorporating combined biological‐photochemical decomposition , 1999 .

[56]  Louis I. Gordon,et al.  Oxygen solubility in seawater : better fitting equations , 1992 .

[57]  T. R. Anderson,et al.  Chapter 16 – Modeling DOM Biogeochemistry , 2002 .

[58]  Dennis A. Hansell,et al.  Mineralization of dissolved organic carbon in the Sargasso Sea , 1995 .

[59]  John Marra,et al.  An Alternative Algorithm for the Calculation of Primary Productivity from Remote Sensing Data , 2003 .

[60]  Richard A. Feely,et al.  Impact of Anthropogenic CO2 on the CaCO3 System in the Oceans , 2004, Science.

[61]  Scott C. Doney,et al.  Evaluation of ocean model ventilation with CFC-11: comparison of 13 global ocean models , 2002 .

[62]  S. Emerson Seasonal oxygen cycles and biological new production in surface waters of the subarctic Pacific Ocean , 1987 .

[63]  S. Levitus,et al.  Distribution of nitrate, phosphate and silicate in the world oceans , 1993 .

[64]  François Primeau,et al.  Optimization and sensitivity study of a biogeochemistry ocean model using an implicit solver and in situ phosphate data , 2006 .

[65]  J. Minster,et al.  Dissolved organic carbon in the equatorial Atlantic Ocean , 1995 .

[66]  François W. Primeau,et al.  Sensitivity and Optimization Study of a Biogeochemistry Ocean Model using an Implicit Solver and In-Situ Phosphate Data , 2006 .

[67]  R. Feely,et al.  Relating estimates of CaCO3 production, export, and dissolution in the water column to measurements of CaCO3 rain into sediment traps and dissolution on the sea floor: A revised global carbonate budget , 2007 .

[68]  P. Renaud,et al.  Distributions of TOP, TON and TOC in the North Pacific subtropical gyre : Implications for nutrient supply in the surface ocean and remineralization in the upper thermocline , 2000 .

[69]  Dennis A. Hansell,et al.  Horizontal and vertical removal of organic carbon in the equatorial Pacific Ocean: a mass balance assessment , 1997 .

[70]  E. Boyle,et al.  Is AOU a good measure of respiration in the oceans? , 2004, Geophysical Research Letters.

[71]  Jorge L. Sarmiento,et al.  Redfield ratios of remineralization determined by nutrient data analysis , 1994 .

[72]  S. Wakeham,et al.  A new, mechanistic model for organic carbon fluxes in the ocean based on the quantitative association of POC with ballast minerals , 2001 .

[73]  E. Peltzer,et al.  A timescale for dissolved organic carbon production in equatorial Pacific surface waters , 1997 .

[74]  R. Fine,et al.  Global oceanic chlorofluorocarbon inventory , 2004 .

[75]  R. Wanninkhof Relationship between wind speed and gas exchange over the ocean , 1992 .

[76]  H. Ducklow,et al.  Annual flux of dissolved organic carbon from the euphotic zone in the northwestern Sargasso Sea , 1994, Nature.

[77]  R. Najjar,et al.  A global monthly climatology of phosphate, nitrate, and silicate in the upper ocean: Spring‐summer export production and shallow remineralization , 2000 .

[78]  Carlo H. R. Heip,et al.  Denitrification in marine sediments: A model study , 1996 .

[79]  W. Berelson,et al.  The Flux of Particulate Organic Carbon Into the Ocean Interior: A Comparison of Four U.S. JGOFS Regional Studies , 2001 .

[80]  J. Marotzke,et al.  The wind‐driven, subtropical gyres and the solubility pump of CO2 , 2002 .

[81]  P. Delecluse,et al.  OPA 8.1 Ocean General Circulation Model reference manual , 1998 .

[82]  P. Falkowski,et al.  Photosynthetic rates derived from satellite‐based chlorophyll concentration , 1997 .

[83]  J. Sarmiento,et al.  Oceanic ventilation and biogeochemical cycling: Understanding the physical mechanisms that produce realistic distributions of tracers and productivity , 2004 .

[84]  Richard A. Feely,et al.  A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP) , 2004 .

[85]  B. Peterson,et al.  Particulate organic matter flux and planktonic new production in the deep ocean , 1979, Nature.

[86]  Thomas F. Stocker,et al.  A latitude-depth, circulation-biogeochemical ocean model for paleoclimate studies. Development and sensitivities , 1998 .

[87]  E. Yu,et al.  Trapping efficiency of bottom-tethered sediment traps estimated from the intercepted fluxes of 230Th and 231Pa , 2001 .

[88]  J. Newton,et al.  Export flux of particulate organic carbon from the central equatorial Pacific determined using a combined drifting trap-234Th approach , 1996 .

[89]  E. Maier‐Reimer,et al.  Evaluation of OCMIP-2 ocean models' deep circulation with mantle helium-3 , 2004 .

[90]  Synte Peacock Debate over the ocean bomb radiocarbon sink: Closing the gap , 2004 .

[91]  Scott C. Doney,et al.  Evaluating global ocean carbon models: The importance of realistic physics , 2004 .

[92]  W. Jenkins 3H and 3He in the Beta Triangle: Observations of Gyre Ventilation and Oxygen Utilization Rates , 1987 .

[93]  James C. McWilliams,et al.  Sensitivity to Surface Forcing and Boundary Layer Mixing in a Global Ocean Model: Annual-Mean Climatology , 1997 .

[94]  Nicholas R. Bates,et al.  Pelagic functional group modeling: Progress, challenges and prospects , 2006 .

[95]  V. Smetácek,et al.  Spring bloom initiation and Sverdrup's critical‐depth model , 1990 .

[96]  A. Watson,et al.  Carbon Dioxide Fluxes in the Global Ocean , 2003 .

[97]  Philip B. Duffy,et al.  Effects of Subgrid-Scale Mixing Parameterizations on Simulated Distributions of Natural 14C, Temperature, and Salinity in a Three-Dimensional Ocean General Circulation Model , 1997 .

[98]  Ralph F. Keeling,et al.  Seasonal and interannual variations in atmospheric oxygen and implications for the global carbon cycle , 1992, Nature.

[99]  Global Ocean Storage of Anthropogenic Carbon (GOSAC) , 2002 .

[100]  Dennis A. Hansell,et al.  Net community production of dissolved organic carbon , 1998 .

[101]  F. Joos,et al.  Water mass distribution and ventilation time scales in a cost-efficient, three-dimensional ocean model , 2006 .

[102]  Y. Yamanaka,et al.  The role of the vertical fluxes of particulate organic matter and calcite in the oceanic carbon cycle: Studies using an ocean biogeochemical general circulation model , 1996 .

[103]  S. Myklestad,et al.  Dynamics of DOC in the Norwegian Sea inferred from monthly profiles collected during 3 years at 66°N, 2°E , 1997 .

[104]  J. Sarmiento,et al.  Oxygen and nitrate new production and remineralization in the North Atlantic subtropical gyre , 1990 .

[105]  J. Sarmiento,et al.  Oceanic vertical exchange and new production: a comparison between models and observations , 2001 .

[106]  J. Goering,et al.  UPTAKE OF NEW AND REGENERATED FORMS OF NITROGEN IN PRIMARY PRODUCTIVITY1 , 1967 .