@String{GCB = {Global Change Biology}} @String{JPConf = {J. Phys.: Conf. Ser.}} @Article{Randerson:GCB:2009, author = {James T. Randerson and Forrest M. Hoffman and Peter E. Thornton and Natalie M. Mahowald and Keith Lindsay and Yen-Huei Lee and Cynthia D. Nevison and Scott C. Doney and Gordon Bonan and Reto St\"ockli and Curtis Covey and Steven W. Running and Inez Y. Fung}, title = {Systematic Assessment of Terrestrial Biogeochemistry in Coupled Climate-Carbon Models}, journal = GCB, volume = 15, number = 9, pages = {2462--2484}, note = {doi:\href{http://dx.doi.org/10.1111/j.1365-2486.2009.01912.x}{10.1111/j.1365-2486.2009.01912.x}}, month = sep, year = 2009, abstract = {With representation of the global carbon cycle becoming increasingly complex in climate models, it is important to develop ways to quantitatively evaluate model performance against in situ and remote sensing observations. Here we present a systematic framework, the Carbon-LAnd Model Intercomparison Project (C-LAMP), for assessing terrestrial biogeochemistry models coupled to climate models using observations that span a wide range of temporal and spatial scales. As an example of the value of such comparisons, we used this framework to evaluate two biogeochemistry models that are integrated within the Community Climate System Model (CCSM) --- Carnegie-Ames-Stanford Approach$'$ (CASA$'$) and carbon–nitrogen (CN). Both models underestimated the magnitude of net carbon uptake during the growing season in temperate and boreal forest ecosystems, based on comparison with atmospheric CO$_2$ measurements and eddy covariance measurements of net ecosystem exchange. Comparison with MODerate Resolution Imaging Spectroradiometer (MODIS) measurements show that this low bias in model fluxes was caused, at least in part, by 1--3 month delays in the timing of maximum leaf area. In the tropics, the models overestimated carbon storage in woody biomass based on comparison with datasets from the Amazon. Reducing this model bias will probably weaken the sensitivity of terrestrial carbon fluxes to both atmospheric CO$_2$ and climate. Global carbon sinks during the 1990s differed by a factor of two (2.4 Pg C yr$^{−1}$ for CASA$'$ vs. 1.2 Pg C yr$^−1$ for CN), with fluxes from both models compatible with the atmospheric budget given uncertainties in other terms. The models captured some of the timing of interannual global terrestrial carbon exchange during 1988--2004 based on comparison with atmospheric inversion results from TRANSCOM ($r=0.66$ for CASA$'$ and $r=0.73$ for CN). Adding (CASA$'$) or improving (CN) the representation of deforestation fires may further increase agreement with the atmospheric record. Information from C-LAMP has enhanced model performance within CCSM and serves as a benchmark for future development. We propose that an open source, community-wide platform for model-data intercomparison is needed to speed model development and to strengthen ties between modeling and measurement communities. Important next steps include the design and analysis of land use change simulations (in both uncoupled and coupled modes), and the entrainment of additional ecological and earth system observations. Model results from C-LAMP are publicly available on the Earth System Grid. } } @InProceedings{Hoffman:iEMSs:2008, author = {Forrest M. Hoffman and James T. Randerson and Inez Y. Fung and Peter E. Thornton and Yen-Huei ``Jeff'' Lee and Cutis C. Covey and Gordon B. Bonan and Steven W. Running}, title = {The {C}arbon-{L}and {M}odel {I}ntercomparison {P}roject ({C-LAMP}): A Protocol and Evaluation Metrics for Global Terrestrial Biogeochemistry Models}, editor = {Miquel S\`{a}nchez-Marr\`{e} and Javier B\'{e}jar and Joaquim Comas and Andrea E. Rizzoli and Giorgio Guariso}, booktitle = {Proceedings of the i{EMS}s Fourth Biennial Meeting: International Congress on Environmental Modelling and Software (i{EMS}s 2008)}, ISBN = {978-84-7653-074-0}, address = {Barcelona, Catalonia, Spain}, month = jul, year = 2008 abstract = {Described here is a protocol and accompanying metrics for evaluation of scientific model performance of global terrestrial biogeochemistry models. Developed under the guise of the NCAR Community Climate System Model (CCSM) Biogeochemistry Working Group, the Carbon-Land Model Intercomparison Project (C-LAMP) experimental protocol improves and expands upon the Coupled Carbon Cycle-Climate Model Intercomparison Project (C$^4$MIP) Phase 1 protocol. However, unlike traditional model intercomparisons, C-LAMP has established scientific model performance metrics based upon comparison against best-available satellite- and ground-based measurements. Moreover, C-LAMP has partnered with the U.S. Department of Energy's Program for Climate Model Diagnosis and Intercomparison (PCMDI) to collect, archive, and distribute---via the Earth System Grid (ESG)---model results from C-LAMP experiments performed by international modeling groups in the same fashion as was done for the model results used in the Intergovernmental Panel on Climate Change (IPCC) Fourth Assessment Report (AR4). In addition, because future IPCC Assessment Reports are expected to be based on results from integrated Earth System Models (ESMs), C-LAMP is helping to establish the metadata standards for model output from terrestrial biogeochemistry components of ESMs. Proposed as an extension to the netCDF Climate and Forecast (CF) 1.1 Convention, these metadata standards will facilitate future model-model and model-measurement intercomparisons. A prototype diagnostics tool has been developed for C-LAMP that summarizes model results, produce graphical representations of these results as compared with observational data sets, and score models on their scientific performance. } } @Article{Hoffman:JPConf:2007, author = {Forrest M. Hoffman and Curtis C. Covey and Inez Y. Fung and James T. Randerson and Peter E. Thornton and Yen-Huei Lee and Nan A. Rosenbloom and Reto C. St\"ockli and Steven W. Running and David E. Bernholdt and Dean N. Williams}, title = {Results from the {C}arbon-{L}and {M}odel {I}ntercomparison {P}roject ({C-LAMP}) and Availability of the Data on the {E}arth {S}ystem {G}rid ({ESG})}, journal = JPConf, volume = 78, pages = {012026 (8pp)}, doi = {10.1088/1742-6596/78/1/012026}, note = {doi: \href{http://dx.doi.org/10.1088/1742-6596/78/1/012026}{10.1088/1742-6596/78/1/012026}}, month = dec, year = 2007, abstract = {This paper describes the Carbon-Land Model Intercomparison Project (C-LAMP) being carried out through a collaboration between the Community Climate System Model (CCSM) Biogeochemistry Working Group, a DOE SciDAC-2 project, and the DOE Program for Climate Model Diagnosis and Intercomparison (PCMDI). The goal of the project is to intercompare terrestrial biogeochemistry models running within the CCSM framework to determine the best set of processes to include in future versions of CCSM. As a part of the project, observational datasets are being collected and used to score the scientific performance of these models following a well-defined set of metrics. In addition, metadata standards for terrestrial biosphere models are being developed to support archival and distribution of the C-LAMP model output via the Earth System Grid (ESG). Progress toward completion of this project and preliminary results from the first set of experiments are reported.} }