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Isotopes in the CCSM

Isotopes in the CCSM. No resources in NCAR: community effort NCAR efforts to organize: Andrew Gettelman and Natalie Mahowald Identify priorities Identify gaps/complementary and overlaping activities Make plan to implement water and carbon dioxide isotopes into CCSM

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Isotopes in the CCSM

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  1. Isotopes in the CCSM • No resources in NCAR: community effort • NCAR efforts to organize: Andrew Gettelman and Natalie Mahowald • Identify priorities • Identify gaps/complementary and overlaping activities • Make plan to implement water and carbon dioxide isotopes into CCSM • Organizational meeting (June, 2003) : community indicated there was a need for a workshop and plan • CCSM Isotope workshop (Jan, 2004): Identified Science questions, Priorities and Work plan (with Inez Fung and Bette OttoBliesner on organizational committee)

  2. Water Isotopes can help address following science questions • Paleoclimate (many proxies are isotopes) • Upper troposphere/lower stratospheric transport • Water cycle improvements • Improve parameterizations of cloud processing, transport • Improve understanding • Surface Water budget • Ocean circulation • Need for some carbon • dioxide isotopes Figure courtesy of Gavin Schmidt

  3. Carbon dioxide isotopes (delO18) • Can provide information about sources and sinks of carbon dioxide in atmosphere and plants • Intimately linked with water isotopes in the plants • Requires links to water in soils and plants Figure courtesy of Chris Still

  4. Carbon dioxide isotopes • (C13) Differentiates between different land sources and sinks of carbon dioxide (land, ocean, C3/C4 plants) • (C14-bomb C14) Provides information about reservoir lifetimes of carbon in different pools (e.g. woody mass, roots, etc.)

  5. Work Plan • Priorities: (1) Water Isotopes, (2) Carbon dioxide isotopes • Water Isotopes: ongoing work by • David Noone (CU), Sun Wong (Maryland), Andrew Gettelman (NCAR) • Jung Eun Lee (UCB) simple approach • Difficulties: • Moving target (CCM3-CAM2->CAM3) • Problems in physics, transport code makes water isotopes difficult to implement • Few NCAR resources (need to incorporate into development branch, etc.)

  6. Carbon dioxide isotopes (work plan) • Entrepeneurial work by: • Bill Riley, Chris Still and David Noone to incorporate delO18 isotopes into CLM (from LSM) • Scott Denning and Neil Suits to incorporate delC13 into CLM • delC14 ?(relatively easy once above done, but no plan) • Ocean model isotopes (tracer work in progress) • Problems • Moving targets (LSM vs. CLM), hopefully reduced in future • Needs many new features (e.g. new tracers advected in plants in CLM) • Lack of BGC resources (land working group supportive)

  7. CAM2 - Precipitation Weighted Annual Mean 18O in Precipitation CAM2 GNIP Obs. • Reasonable first simulation of water isotopes in precipitation in CAM2. Jung-Eun Lee and Inez Fung

  8. Mean Annual D in vapor CAM2 • Observed • Nebraska, USA (Ehhalt, 1974) • Heidelberg, Germany (Taylor, 1972: only up to 5 km) • Stratosphere (Pollock, 1980) • From Araguas-Araguas • et al., 2000 • CAM 2 captures general feature of the vertical profile of water isotopes in vapor. • But minimum value too low--first guess: need more condensate in CAM2 upper tropopause, oxidation of methane (?) Jung-Eun Lee and Inez Fung

  9. CCM3 prototype David Noone

  10. What BGCWG (and other working groups) can do: • Identify isotopes in the model as a priority to the CCSM so that resources are allocated to implement and support the codes.

  11. New areas • Iron cycle (atmosphere (Mahowald) and ocean (Moore)) • Nitrogen cycle—land (Thornton) and atmosphere (Lamarque/Hess) • Sulfur cycle--? (atmosphere ready, ocean?) • River biogeochemistry • Coastal biogeochemistry • Ocean Sediment model • Isotopes • Fires • Phosphate (no need to couple?)

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