Ecosystem Model-Data Intercomparison
The next Ecosystem Model/Data Intercomparison will be held 18-21 April, 2001 and is jointly sponsored by GAIM and the National Center for Ecological Analysis and Synthesis (NCEAS) in Santa Barbara, California. The first EMDI workshop included 12 biogeochemical, satellite-driven, detailed process, and dynamic vegetation global model types. The EMDI II Participants will include all modeling groups from the first, except one (model is no longer supported) and has expanded to include 5 additional groups for a grand total of 16 global terrestrial ecosystem models. The participating modelers will utilize data sets that have been improved through outlier analysis and perform new model runs for a set of approximately 4000 0.5° grid cells. Whereas the analysis in EMDI I was based on comparing ensemble values averaged from all 12 models strictly for total (above and belowground) NPP, EMDI II will compare model results with NPP data for individual models and also require models to supply above and belowground NPP estimates to assess how models allocate carbon in various biomes relative to the data. In addition, multi-year NPP estimates for a variety of sites to will be compared to interannual model estimates. In addition to the analysis of differences between models and data, EMDI will produce an enhanced multi-layered data collection, again that will ultimately be made available for additional use by the wider scientific community. The enhancements include associating climate, soils, NDVI, and vegetation characteristics with each of the NPP measurements, and performing an outlier analysis to address data quality concerns.

In addition to the comparisons, participants at the April workshop will refine the current draft of the paper describing the "ensemble" results from the first workshop. Future directions for EMDI will also be discussed. Current proposals include the inclusion of transient analyses to test models and data against data collected from tower flux sites.