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Ocean Biogeochemistry Nicholas Stephens Max-Planck-Institut für Biogeochemie, Jena

Ocean Biogeochemistry Nicholas Stephens Max-Planck-Institut für Biogeochemie, Jena. Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 1/18. Aims of present studies. Synthesise current understanding/ experimental findings N 2 and N cycle

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Ocean Biogeochemistry Nicholas Stephens Max-Planck-Institut für Biogeochemie, Jena

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  1. Ocean BiogeochemistryNicholas StephensMax-Planck-Institut für Biogeochemie, Jena Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 1/18

  2. Aims of present studies • Synthesise current understanding/ experimental findings • N2 and N cycle • Associated biology • Ocean processes • Decoupling of N:P Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 2/18

  3. Aims of present studies • DGOP goal is to build global biogeochemistry models based on PFT’s • Understand and quantify the feedbacks between marine ecosystems and climate Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 3/18

  4. The role of biology • Resulting C fluxes and DIC concentrations are affected by photoautotrophic C fixation • C fixation and the contribution to export is a function of community structure and physiology • Growth is regulated by availability of other nutrients (DIN, PO4, Fe), and physical variables such as temp Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 5/18

  5. Ocean-atmosphere carbon fluxes Nitrogen fixation IPCC, third assessment Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 4/18

  6. Effects on biogeochemical cycles Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 6/18

  7. Present model: PlankTOM6.0 Light DIN PO4 Fe Si Nanophytoplankton N2 fixers Diatoms Calcifiers Bacterial remineralisation Microzoo-plankton Mesozoo-plankton Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 7/18

  8. Limitation of growth due to NO3 Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 8/18

  9. Limitation of growth due to PO4 Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 9/18

  10. Temperature relationship of N2-fixing PFT Staal et al. 2003 La Roche and Breitbarth, 2005 Carpenter et al. 2004 Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 10/18

  11. strategy for forced atmospheric conditions Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 11/18

  12. Results for a PlankTOM6.0 2005 October simulation Silicifiers Mixed Phytoplankton µmolC L-1 Calcifiers N2 fixers N2 fixed = 0.171 PgN yr-1, Primary Productivity = 71.08 PgC yr-1, Export to 100m = 13.05 PgC yr-1 Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 12/18

  13. Simulated monthly mean N2 fixer concentration, April 2005 µmolC L-1 Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 13/18

  14. Comparison to remote sensing information Westberry et al. 2006 Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 14/18

  15. The Working Group on Coupled Modelling (CLIVAR/WCRP) took place in September 2006. This working group guides the development of the Coupled Models which are used by hundreds of scientists to project the future state of climate, and evaluate those projections (e.g. the IPCC model archive). Here is a brief report of the state of the carbon cycle presented by Corinne Le Quéré during the September meeting. Full version available at c.lequere@uea.ac.uk Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 15a/18

  16. Ongoing model developments • On land: • fires • land use • CH4 cycle • N cycle • more advance ecosystem dynamics (including competition and succession) • Unresolved issues: • importance of CO2 fertilisation • importance of forest regrowth • temperature dependence of soil respiration • CH4 budget • In the oceans: • more advanced ecosystem dynamics (incl. grazers and incl. major efforts on biological data synthesis) • relaxation of N/P ratio and quota models • coastal ocean dynamics (over years) • links with higher trophic levels • Unresolved issues: • importance of ecosystem dynamics • impact of ocean acidification on ecosystems • impact of recent changes in ocean physics and temperature (including on respiration) Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 15b/18

  17. Issues on the C-Cycle • C-cycle - climate feedbacks will increase before they are constrained • C-cycle – CO2 feedbacks will increase before they are constrained • C-cycle - climate feedbacks are highly dependent on the water cycle • standards and archiving of C-cycle variables not organized • Issues for model inter-comparison (C4MIP): • fragmented understanding of the processes • limited observations for validation • incomplete models, thus they should not be expected to reproduce observation (e.g. no fires, no land use) • no financial support for C4MIP activities • no standards • no shared 3D fields • no archiving strategy Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 15c/18

  18. Present activities • Stephens N. and Flynn KJ. in prep. “Nitrogen-status of Gloeothece sp. cells reflects growth supported by different inorganic nitrogen sources” • Stephens N. et al.in prep “Including N2 fixation as a Plankton Functional Type in a Dynamic Green Ocean Model” • Stephens N. in prep. “Nitrogen fixation and inorganic nitrogen assimilation in the cyanobacterium Trichodesmium spp. can be described using a mathematical model. • Allen et al. in prep. “Evaluating and validating Plankton Functional Type models” as part of a recent AMEMR workshop Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 16/18

  19. Future plans • Preparation of the PlankTOM10.0 model for coupling to the QUEST coupled model • Preparation of the PlankTOM10.0 model for publication • Investigating the response of the nitrogen cycle and implications for climate due to changing physical conditions Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 17/18

  20. Acknowledgements • Corinne Le Quéré, Erik Buitenhuis and members of the Green Ocean Project • Greencycles Project • Marie Curie Actions • MPI-BGC, Jena • UEA Nick Stephens Greencycles Mid-Term Review meeting 21/02/2007 18/18

  21. Dust deposition (μmol N kg-1 month-1) World Ocean Atlas 2001

  22. Bergman, botan website Trichodesmium erythraeum

  23. 16 Mean N:P (μmol N kg-1/μmol P kg-1) World Ocean Atlas 2001

  24. Regulation of N2 fixation Leakage/lysis N2 fix/uptake DIN Phyto-uptake Remineralisation Diatom-uptake Physical processes Cocco-uptake

  25. N2 DIN Decay PO4 N2 fixer Sedimentation Fe Heterotrophy O2

  26. Summary • Significance of biogeochemical processes and feedbacks • N cycle leads to better representation of fluxes of C • N2 fixation needs a relationship to N • Denitrification requires more substantial relationship to P

  27. latest developments are done with NEMO, running on a linux cluster at the Univ. of East Angliasome developments done with OPA8.1, running on the German DKRZ super-computerwe do mostly interannual simulations with NCEP forcingwe focus on CO2, O2, and marine ecosystemslarge parallel data synthesis

  28. PlSCES-T • limitation by Fe, P, and Si • Meso-zooplankton parameterisation based on global data compilation (difference to Olivier Aumont's PISCES model) phyto-plankton mixed silicifiers proto zoo-plankton meso

  29. PlankTOM 5 • limitation by Fe, P, and Si • Meso-zooplankton parameterisation based on global data compilation • Micro-zooplankton parameterisation based on global data compilation (work with Richard Rivkin) • Ballast effect based on Stokes law • adjusted grazing preferences phyto-plankton calcifiers mixed silicifiers proto zoo-plankton meso

  30. bacteria pico-heterotrophs PlankTOM 9 (under development) pico-autotrophs N2-fixers phyto-plankton calcifiers DMS-producers mixed silicifiers proto zoo-plankton meso

  31. bacteria pico-heterotrophs proto zoo-plankton meso macro PlankTOM 10 (planned for 2007) pico-autotrophs N2-fixers phyto-plankton calcifiers DMS-producers mixed silicifiers

  32. PlankTOM 6.0 simulation for 1st October 2005 N2 fixers Coccolithophores N2 fixed = 0.171 PgN yr-1, Primary Productivity = 96.60 PgC yr-1, Export to 100m depth = 16.27 PgC yr-1 Diatoms Mixed phytoplankton

  33. Projection of atmospheric CO2 up to 2060

  34. anomalies in atmospheric forcing north equator south Temperature (oC) Precipitations (m yr-1) zonal wind stress (N m-2)

  35. model projection of climate change in 2060 temperature mixed layer depth ice cover

  36. PlankTOM Fe PO4 Calcifiers PISCES-T change in the CO2 sink in 2060 (mol/m2/y)

  37. Laurent’s thesis -30 % +30 % Comparison to results from the thesis of Laurent Bopp export production at 100 m for 2xCO2 PISCES-T PlankTOM-5

  38. Prototype of the PlankTOM 10 Dynamic Green Ocean Model Heterotrophic bacteria and Archaea pico-heterotrophs 10 Plankton Functional Types (PFTs) selected for (a) their explicit biogeochemical role, (b) quantitative importance in at least one region of the ocean, (c) a distinct set of environmental and nutrient requirements for productivity, (d) a distinct impact on the rest of the community (e.g. composition). pico-autotrophs N2-fixers calcifiers phyto-plankton DMSp-producers mixed silicifiers proto zoo-plankton meso macro

  39. Other DGOMs under construction with similar (but not identical) choices of PFTs: • ERSEM global (M. Vichi, I. Allen) • PISCES + (O. Aumont) • NEMURO (Y. Yamanaka) • BEC (K. Moore + S. Doney) • Hamocc5 (E. Maier-Reimer) • Gregg (W. Gregg et al.)

  40. data available for parameterisation meso-zooplankton growth phytoplankton growth Based on IRONAGES results (C. Lancelot et al.) Buitenhuis et al., 2006

  41. data available for parameterisation Even where an abundance of data exists does not necessarily imply well constrained parameters

  42. data available for parameterisation and evaluation

  43. data available for parameterisation and evaluation • The only exhaustive (>5000 points) insitu database of biomass concentration exists for meso-zooplankton. Efforts are underway for a similar database on proto-zooplankton • Gregg et al. have a database on percent distribution of ~500 data points • The EU euroceans project has some funding for building a data base of PFT concentration before 2009, but it is not clear how much effort is needed.

  44. data available for parameterisation and evaluation Mesozooplankton biomass (µmol C L-1)

  45. data available for parameterisation and evaluation • A few algorithms can detect phyto-PFT from space (but they also need evaluation) PHYSAT PFTs (January 98-05 synthesis map) Alvain et al., 2005

  46. data available for parameterisation and evaluation • geochemical data can be used to assess that the sum of the processes is correct (e.g. biological, chemical, and physical). The data include concentrations of DIC, TALK, Si, PO4, NO3 and O2.

  47. data available for parameterisation and evaluation the absolute top priority to evaluate DGOMs is to fill this table Especially biomass

  48. N:C calculations for batch cultures of Gloeothece Stephens, unpublished

  49. Estimates for pelagic N2 fixation • N2 fixation ~100-200 Tg N yr-1 (Sarmiento and Gruber, 1997) • Denitrification estimated ~450 Tg N yr-1 • Capone et al. 2005 estimates for N2 fixation in the N Atlantic are 3-4 times Sarmiento and Gruber (1997) estimates for same region • Short residence times of N (<3000 yr) have potential for substantial change in N inventory • N2 fixation is part of a very dynamic ocean N cycle

  50. Estimates for pelagic N2 fixation based fluxes per area in the Atlantic Ocean • 5.5 – 8.7 T mol N yr-1 = 77 – 121.8 T gN yr-1 • C:N = 4.7 – 7.3 for Trichodesmium • 361.9 - 889.14 T gC yr-1 • just for a 28 M km2 area of the N Atlantic! • Considering only Trichodesmium • Estimates for new N considered conservative Capone, 2005; Sarmiento and Gruber, 1997; La Roche and Breitbarth, 2005

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