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Towards Quantitative Evaluation of Ocean Tracer Model Simulations

34 th International Liège Colloquium Tracer Methods in Geophysical Fluid Dynamics 6 May 200 2. Towards Quantitative Evaluation of Ocean Tracer Model Simulations. J . C. Orr 1 , K. G. Caldeira 2 , K. E. Taylor 3 and the OCMIP Group* 1 LSCE/CEA/CNRS and IPSL (France) 2 LLNL

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Towards Quantitative Evaluation of Ocean Tracer Model Simulations

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  1. 34th International Liège Colloquium Tracer Methods in Geophysical Fluid Dynamics 6 May 2002 Towards Quantitative Evaluation of Ocean Tracer Model Simulations J. C. Orr 1, K. G. Caldeira 2, K. E. Taylor 3and the OCMIP Group* 1LSCE/CEA/CNRS and IPSL (France) 2LLNL 3PCMDI / LLNL http://www.ipsl.jussieu.fr/OCMIP

  2. OCMIP-2 Group • AWI(Bremerhaven, Germany): R. Schlitzer, M.-F. Weirig • CSIRO(Hobart, Australia): R. Matear • IGCR/CCSR (Tokyo, Japan): Y. Yamanaka, A. Ishida • IPSL (LSCE, LODyC, Paris, France): J. Orr, P. Monfray, O. Aumont, J.-Cl.Dutay, P. Brockmann • LLNL(Livermore, CA, USA):K. Caldeira, M. Wickett • MIT(Boston, USA): M. Follows, J. Marshall • MPIM (Max Planck Institut fuer Meteorologie – Hamburg, Germany): E. Maier-Reimer • NCAR (Boulder, CO, USA): S. Doney, K. Lindsay, M. Hecht • NERSC (Bergen, Norway): H. Drange, Y. Gao • PIUB (Bern, Switzerland): F. Joos, K. Plattner • PRINCEton (Princeton, USA): J. Sarmiento, A. Gnanadesikan, R. Slater, R. Key • SOC (Southampton Oceanography Centre/ Hadley Center, UK): I. Totterdell, A. Yool • UL (University of Liege/University Catholique de Louvain, Belgium): A. Mouchet, E. Deleersnijder, J.-M. Campin • PMEL/NOAA (Seattle, USA): J. Bullister, C. Sabine • PSU (Penn. State, USA): R. Najjar, F. Louanchi • UCLA (Los Angeles, USA): N. Gruber, X. Jin

  3. The OCMIP-2 models differ Resolution Seasonality Boundaryconditions Sub-grid mixing Mixed Layer Sea-ice Model Offline/Online

  4. How Good is a Model? • Relative to data • Relative to other models • Skill assessment depends on • Our Objectives (e.g., mean state vs. variability) • Our Vision • Rose colored glasses • Dark Sunglasses • Clear glasses? • Local, Qualitative Analysis • Global, Quantitative Analysis

  5. OCMIP-2 Simulations • Tracers • CFC-11 and CFC-12 • Natural C-14 and Bomb C-14 • He-3 and He-4 • Carbon • Preindustrial: • Abiotic • Common Biogeochemistry (∑CO2, Alk, PO4, O2, DOM) • Preindustrial to Present • Future (two IPCC scenarios: IS92a, S650) • Sequestration (7 sites, 3 depths, 2 scenarios) 3-

  6. Global OceanAnnual Mean Sea-Air CO2 Flux in 1995 (mol m-2 yr-1)

  7. A Useful Diagram* Some Summary Statistics Key relationship: • Standard deviations • reference • model • Correlation Coefficient R: • Centered Pattern RMS error: • Overall Bias: Law of Cosines: *Taylor, K.E., J. Geophys. Res., 106, D7, 7183-7192, 2001

  8. Taylor Plot: Sea-Air CO2 Flux (1995 Annual Mean, Global Map)

  9. Taylor Plot: Sea-Air CO2 Flux (1995 Full Global Space-Time Distribution)

  10. Basin Zonal IntegralsAnnual Mean Sea-Air CO2 Flux in 1995 (Pg C yr-1 deg-1)

  11. GlobalSeasonalZonal Integral Sea-Air CO2 Flux in 1995 (Pg C yr-1 deg-1)

  12. Sea-Air CO2 Flux: Pacific Ocean Equatorial Pacific: 22oS-22oN North Pacific: 22oN-70oN

  13. Conclusions: Total CO2 validation • Taylor* Diagram: graphical evaluation of 5 global summary statistics (σdata,σmodel, r, R.M.S., Bias) • Provides quick, global roadmap • Motivates further evaluation • Not mechanistic • Air-sea CO2 flux • OCMIP-2 models succeed in terms of zonal mean • OCMIP-2 models fail in terms of zonal and seasonal anomalies *Taylor, K. E., J. Geophys. Res., 106, D7, 7183-7192, 2001

  14. Taylor Plot for Deep 14C (below 1000 m)

  15. Natural 14C (West Atlantic, GEOSECS Section) Some models under-predict 14C Some models over-predict 14C

  16. Data Pacific OceanWOCE P16 14C Some models over-predict 14C Some models under-predict 14C

  17. CFC-11 in the South Atlantic Ajax Data Some models under-predict CFC uptake Some models over-predict CFC uptake Dutay et al., Ocean Modell., 2001

  18. Anthropogenic CO2 uptake is correlated with CFC-11 uptake and ∆14C Global CFC-11 Inventory (1989) Mean ∆14C below 1000 m

  19. Sabine et al., 2001 Data-based estimate Simulated 1995anthropogenic CO2 columninventories Some models take up a lot of CO2 in the Southern Ocean Some models take up little CO2 in the Southern Ocean

  20. Global air-sea anthropogenic CO2 flux (Pg C yr-1)

  21. Summary of OCMIP2 anthropogenic CO2 simulations • Some agreement on global historical CO2 uptake by the ocean • For the 1980’s = 2.0 ± 0.4 PgC yr–1 • For the 1990’s • IS92a = 2.5 PgC yr–1 • adjusted IS92a = 2.2 PgC yr–1 • Some disagreement on regional and future fluxes • 1980’s and 1990’s +/-13% (about the mean) • Year 2100 +/-20% (IS92a and S650) • Year 2300 +/-35% (S650)

  22. Rationale for CO2 uptake estimate • Observed natural ∆14C values are within the range of model results. • Modeled CO2 uptake is correlated with modeled ∆14C • Observed CFC-11 concentrations are within the range of model results • Modeled CO2 uptake is correlated with modeled [CFC-11] • Independently estimated anthropogenic CO2 inventories are within the range of model results • Therefore, anthropogenic CO2 uptake by the real ocean is probably within the range of model results. • Ocean CO2 uptake for the 1980’s = 2.0 ± 0.4 PgC yr–1 • IS92a 1990’s = 2.5 PgC yr–1 • Adjusted IS92a 1990’s = 2.2 PgC yr–1

  23. Back-up slides

  24. Efficiency of deep CO2injection is also correlated with CFC-11 uptake and ∆14C Global CFC-11 Inventory (1989) Mean ∆14C below 1000 m

  25. Global Sea-Air CO2 Flux in 1995 (Zonal Integral, Annual Mean, Pg C yr-1 deg-1)

  26. Pacific Sea-Air CO2 Flux in 1995 (Zonal Integral, Annual Mean, Pg C yr-1 deg-1)

  27. Anthropogenic CO2 vs. CFC-11 Gruber et al., 2001

  28. Large model differences in the Southern Ocean Simulated 1995 cumulative CO2 fluxes and inventory

  29. US Groups are anticipating funding • Inverse basis function simulations • Gruber et al. • Automated Model Ocean Diagnosis (AutoMOD), companion to NOCES, focusing on NASA data products • Caldeira et al.

  30. Next steps • Special OCMIP2 section in Global Biogeochemical Cycles • IGBP open workshop “Global issues in ocean biogeochemistry” • May or June 2002 • GAIM, CLIVAR, JGOFS, GLOBEC, LOICZ, SOLAS • EurOCMIP3 project (NOCES) • Emphasis on interannual to interdecadal variability • A wide range of model types (5 global ocean models, 1 regional ocean model, 1 inverse atmospheric inverse model) • US proposals expecting funding • Inverse basis function simulations (Niki Gruber) • Automated Model Ocean Diagnosis (Ken Caldeira)

  31. Global Biogeochemical CyclesOCMIP2 Special Section • An overiew and history of OCMIP • J. Orr and N. Gruber • Comparison of model physics relevant to the carbon Cycle in OCMIP2 • K. Lindsay (NCAR) • OCMIP2 evaluation of deep-ocean circulation deduced from 3He and 4He simulations • J. Dutay (LSCE) • Efficiency of purposeful CO2 injection in the deep ocean: comparison of the OCMIP2 models • J. Orr (LSCE) • Air-sea fluxes and north-south ocean transport of CO2 and O2: results from OCMIP2 • P. Monfray (LSCE) • Comparison of new and export production from the OCMIP2 models • R. Najjar (Penn State) • Simulations of historical and future anthropogenic CO2 uptake from OCMIP2 models • J. Orr (LSCE) • Comparisons of model- and data-based estimates of anthropogenic CO2 in the oceans • C. Sabine (PMEL)

  32. Proposed IGBP open workshop • TITLE: Global Scale Issues in Ocean Biogeochemistry • WHERE: Ispra in Italy, (host N.Hoepffner at JRC) • WHEN: May or June 2002 • DURATION: 4 days at least (to give time for plenary discussion) • SIZE: 60 (?) with 20 invited • CO-ORGANIZERS: R.Schlitzer & P.Monfray ? • PURPOSES : • Address big questions in global scale ocean biogeochemistry based on recent data, process modeling, and synthesis • Bridge the gaps between physics, biogeochemistry, and biology • Bridge the gap between people working on observations, process modeling, and global modeling • Stimulate strong concerted action in global scale research • TARGET COMMUNITIES: • CLIVAR, JGOFS, GLOBEC, LOICZ and SOLAS

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