CCSM Biogeochemistry Working Group Report
26 June 2003
A half-day meeting of the CCSM Biogeochemistry Working Group was held at the annual CCSM meeting in June. The highlights of that meeting and several other announcements are given below.
Natalie Mahowald (NCAR) has been appointed to a two-year term as the internal co-chair of the CCSM Biogeochemistry Working Group. Scott Doney and Inez Fung will continue as external co-chairs through July 2004.
The next annual CCSM meeting will be held in Santa Fe, NM in July 2004. The theme will be "Biogeochemistry," and the working group will be asked to supply names for plenary speakers in the next couple of weeks (please send suggestions to Natalie, Inez, or me ASAP).
Copies of the CCSM Strategic Business Plan and Science Plan for 2004-2008 are online at the CCSM site: http://www.cesm.ucar.edu/
The next CCSM BGC Working Group meeting will be held at NCAR, dates yet to be determined but probably in the early spring 2004.
Status of CCSM-1 Carbon-Climate Experiments (Doney, Fung):
An update on the current status of the fully coupled CCSM1 carbon-climate experiments was presented. Over the last several years, active land, ocean, and atmosphere carbon cycle modules have been included into the CCSM1 physical framework lead by Fung, Doney, Lindsay, and John. The land BGC module is based on a merging of CASA biogeochemistry and LSM biogeophysics with additional dynamic allocation and prognostic LAI and leaf phenology. The ocean module is based on a full depth carbon, phosphorus, oxygen model developed for OCMIP-2 with the addition of fully prognostic production and an active iron cycle. The goal of the working group is to complete a series of control and fossil fuel emission perturbation simulations in time for submission to the IPCC 4th Assessment (simulations complete by fall2004).
The carbon dynamics is being integrated with the coupled model physics following a sequential spin-up strategy. Biases in the coupled CCSM physical solutions can introduce large drifts in land/ocean/atmosphere carbon inventories, and thus, gradual adjustments are required before the full integration of the atmospheric CO2 with the physics through the radiation terms. Currently, the largest issues arise with the long lived (10-102 yr) land pools (e.g., wood, coarse wood debris, slow soil carbon) and their sensitivity to precipitation and soil moisture. Several multi-century spin-up runs (land-atmosphere; and land-ocean-atmosphere) have been completed with the new land/ocean BGC modules, and we hope to have a new, stable fully coupled control integration running by fall 2003.
Several lessons have been learned in the CCSM1 carbon-climate experience that should be passed on in the development of a CCSM2 carbon climate version. Important issues include spin-up (see above), atmospheric tracer advection, land BGC-biogeophysics interactions (e.g., sensitivity in the coupling between seasonal leaf-out and solar absorption), often subtle physical-BGC numerical issues (e.g., unbounded marginal sea salinities that caused the ocean carbonate thermodynamics code to crash), etc.
Development of BGC components for CCSM2 (Doney, Thornton):
Considerable effort has been devoted within the BGCWG to the development of more sophisticated BGC components for the land and ocean within CCSM2. Plans are also underway to port the CCSM1 BGC modules into CCSM2, so we would have a hierarchy of carbon models of varying complexity. The objective is to have companion CCSM2 carbon climate simulations to those already underway in CCSM1 ready for submission to the IPCC 4th Assessment. Mahowald, Thornton, and Lindsay will lead the integration of the fully coupled CCSM2-carbon.
A fairly sophisticated marine ecosystem model has been implemented within an uncoupled version of the CCSM2 ocean physical model. The ecosystem model includes multiple element cycles (C, P, N, Si, Fe, O) and multiple plankton functional groups (picoplankton, diatoms, diazotrophs, calcifiers). Multi-decade long simulations have been conducted to explore the upper ocean behavior of the systems. Work is underway for longer, quasi-equilibrium simulations to explore coupling with subsurface inorganic carbon and nutrient fields.
A new land BGC model is also being developed within the CLM2 biogeophysical framework. The model explicitly includes nitrogen dynamics and has been extensively tested against data at individual sites. Work is underway for regional and global model-data comparisons in preparation for full coupled experiments later this year or early next year.
Entrepreneurial research and collaborations:
A series of presentations were made on individual and group entrepreneurial research.
E. Holland presented an overview of various research efforts to incorporate Land/Atmosphere biogeochemistry (e.g., ozone deposition, VOC production), and reactive chemistry into the CCSM2.
S. Elliott presented an overview on the DOE/SciDAC effort on biogeochemistry and to facilitate CCSM work.
S. Thompson talked about the coupled carbon-climate simulations being conducted in PCM2.
N. Mahowald and P. Rasch talked about progress on interactive dust generation and atmospheric transport.