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CCSM Biogeochemistry Working Group Report
30 and 31 March 2004
NCAR, Boulder, Colorado


The agenda is listed: http://www.cesm.ucar.edu/working_groups/Biogeo/agendas/040330.pdf.

The talks are available for downloading: http://www.cesm.ucar.edu/working_groups/Biogeo/presentations_2004_spring/.

The discussion was oriented towards deciding new goals for the Biogeochemistry Working Group (BGCWG).  We came up with the following overarching questions, specific tasks, and development gaps in our lengthy discussions.  If you have questions or comments, please contact mahowald@ucar.edu.

Overarching questions that are priorities within the BGCWG:

What are the biogeochemical mechanisms that change and respond to the atmospheric composition and the climate?

1. What are the carbon/climate feedbacks?

How are the natural carbon and climate cycles coupled on seasonal, interannual, decadal, and centennial time scales? How do carbon-climate interactions affect historical and future atmospheric CO2 and climate on centennial time scales?


  • Coupled carbon simulations using simple land and ocean biogeochemistry in CSM1 carbon cycle - runs going now. (Fung/Doney/Lindsay/?Keller?)
  • Coupled land/atmosphere carbon cycle in CCSM3 (C4MIP-Casa'/CCSM3)
    (Hoffman/Fung/John/Levis/Mahowald) - ready
  • Coupled land/ocean/atmosphere in CCSM3 using simple terrestrial and ocean carbon (CASA' and OCMIP') (Hoffman/Fung/Doney/John/Lindsay/Murphy/Mahowald)
2. How do biogeochemical cycles of nitrogen, iron, and sulfur (and other nutrients) influence carbon/climate feedbacks?
  2.1 How does nitrogen cycling modify carbon/climate feedbacks?
  • Coupled carbon with nitrogen (no ocean)--C4MIP-CLM-CN/CCSM3
    (Thornton/Mahowald) - almost ready
  • Offline future nitrogen deposition impacts on CLM/CN - Santa Fe (Lamarque/Thornton/Holland)
  • Coupled carbon with nitrogen (land and ocean) CCSM3 (CLM-CN, Ecosystem)
  • Coupled Chemistry/CAM/CLM-CN/Ocean-ECO (Lamarque/Thornton/Moore/Lindsay /Holland)
  2.2 How does iron impact atmospheric CO2 and climate? (Mahowald/Moore/Thornton/Zender/Doney)
  2.3 How important are ocean sediment/ocean biogeochemistry interactions for carbon uptake by the ocean? (Moore/Elliott/Martin/Sundquist)
  2.4 How does ocean biogeochemistry affect non-carbon dioxide greenhouse gases and climate?
  2.5 How do changes in terrestrial biosphere and dust in last glacial maximum impact the ocean biogeochemistry and atmospheric carbon dioxide, nitrous oxide, and DMS? (Moore/Mahowald/Thornton/Bonan/Collins/Otto-Bliesner/Elliott/Zender)
  2.6 How does phosphorus cycling modify the carbon/climate interaction? (gap - terrestrial phosphorus, riverine, atmospheric (Mahowald), weathering??)
3. How do reactive chemistry and aerosols change and respond to biogeochemical processes, clouds, and climate?
  3.1 How do changing anthropogenic emissions impact ozone and thereby impact terrestrial productivity, atmospheric composition, and climate (including biogenic emissions)? (Hess/Thornton/King/Holland/ Wiedinmyer/Lamarque/Mahowald)
  3.2 How does changing anthropogenic activity impact aerosols and thereby impact terrestrial productivity, atmospheric composition, and climate? (Colllins/Erickson/Mahowald/Rasch/Lamarque/Hess/Wiedinmyer/Thornton/Bonan)
  3.3 What feedbacks occur in the natural aerosol-cloud interactions to modulate climate in the past, present, and future (e.g., DMS, dust, sea salts, fires)? DMS (Elliott/Lamarque/Erickson/Rasch/Collins/Otto-Bliesner)

Dust/sea salts/biomass burning black carbon (Mahowald/Levis/ Rasch/Zender/Collins/Thornton/Randerson/Otto-Bliesner)

Biogenic secondary organic aerosol (Lamarque/Wiedinmyer/ Mahowald/Collins/Hess/Orlando)
  3.4 How are humans modifying clouds and thereby climate through changing aerosol emissions? (Rasch/Ghan/Mahowald/Jensen/Rogers)
  3.5 How did the oxidative capacity change with Holocene and Pleistocene climate?
  3.6 How do volcanoes impact the terrestrial biosphere? (Randerson/Zender/Thornton/Mahowald)
4. How do land use, land cover change, and water use modify biogeochemical processes?
  4.1 How does land use modify biogenic emissions, and thereby modify atmospheric chemistry? (Holland/Weidinmyer/Hess/Levis/Lamarque/ King/Guenther/Bonan)
  4.2 How do land management and disturbance history modify carbon storage and carbon/climate feedbacks? (Thornton/Bonan/Mahowald/Randerson/King)
  4.3 How does fire modify atmospheric chemistry? (Emmons/Hess/Lamarque/Wiedinmyer/Thornton/Mahowald/Randerson/Rasch/Collins)
  4.4 How does human water use modify biogeochemistry, atmospheric composition and climate? (gap)
5. How do hydrological and biogeochemical cycles interact?
  5.1 How important is land/sea runoff for ocean biogeochemistry? (Moore/Nevison/Famiglietti/Sundquist/Branstetter/Rosenbloom/gap from coastal impacts)
  5.2 How do wetlands change and respond to climate? (gap--wetlands-Lamarque/Hess/Bonan//Levis/Holland/Rosenbloom)
  5.3 What is the coupling between the hydrological and carbon cycles? (Bonan/Thornton/Lettenmaier)
  5.4 Coastal-open ocean coupling/regional modeling (Doney, gap...)
Developmental needs:
  Land model:
  • Improved hydrological model (including):
    • Dynamic lake levels
    • Subsurface flow
    • Human water use (reservoirs, irrigation, ...)
    • Wetlands
    • Riverine transport
    • Coastal zones
  • High resolution grid
  • Urban grid cells
  • Updating BVOCs
  • Phosphorus cycle
  • Historical/future? land use disturbance/land-use (and parameterization)
  • Tracers in land model (isotopes)
  • NO, N2O emissions from soils
  • Fire emissions

Atmospheric Chemistry model:

  • Higher resolution grid/urban for chemistry
  • Secondary organic aerosol composition
  • Aerosol microphysics (internal mixtures)
  • Aerosol-cloud microphysics (in progress but could be done better)
  • Fire plume model (chemistry within the plume-wildfire initiative???)
  • Time varying emissions of reactive chemicals
  • Wetland emissions

Ocean model:

  • Coastal ocean parameterization/nested regional models of biogeochemistry and physics
  • Virtual flux/natural boundary conditions for tracers
  • Ocean sediment model
  • Methane and N2O emissions in ocean biogeochemistry
  • VOC emissions from oceans
  • Validated off-line tracer code

Atmosphere model:

  • Downscaling of atmospheric boundary layer to higher resolution land
  • Water isotopes

For all modules: diagnostic tracers for biogeochemical processes (carbon dioxide and water isotopes in land, atmosphere and ocean, C13 fractionation (non MHC, CO>CO2), Sulfur isotopes; C14, HDO, H2dO18, HTO distributions in ocean)

Participant List:

Gordon Bonan, NCAR
Frank Bryan, NCAR
John Drake, ORNL
John Dunne, NOAA
Scott Elliott, LANL
David Erickson, ORNL
Inez Fung, UC Berkeley
Peter Gent, NCAR
Peter Hess, NCAR
Forrest Hoffman, ORNL
Beth Holland, NCAR
Jasmine John, UC Berkeley
Klaus Keller, Pennsylvania State University
Anthony W. King, ORNL
Zav Kothavala, NCAR
J.-F. Lamarque, NCAR
Sam Levis, NCAR
Keith Lindsay, NCAR
Natalie Mahowald, NCAR
Keith Moore, UC Irvine
Sylvia Murphy, NCAR
Bette Otto-Bliesner, NCAR
Synte Peacock, University of Chicago
Nan Rosenbloom, NCAR
Britt Stephens, NCAR
Neil Suits, Colorado State University
Eric Sundquist, USGS
Peter Thornton, NCAR
David X.D. Zeng, University of Arizona


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