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Thomas J. Phillips
Documentation summarizing the numerics and physics of most of the world's atmospheric general circulation models (AGCMs) can now be accessed on the World Wide Web (WWW) at http://www-pcmdi.llnl.gov/phillips/modldoc/amip/amip.html. This information - previously scattered across scores of publications - was centralized by the Program for Climate Model Diagnosis and Intercomparison (PCMDI), which is funded by the U.S. Department of Energy.
The WWW documentation describes the principal features of the AGCMs in use by some 30 modeling centers (Table 1) that are participating in the Atmospheric Model Intercomparison Project (AMIP), an initiative of the World Climate Research Programme (WCRP) that PCMDI coordinates [Gates, 1992]. This information on model properties is a prerequisite for realizing the overall goal of the AMIP: to systematically diagnose and evaluate the performance of current AGCMs in simulating monthly to decadal-scale climate under common specification of radiative forcings and ocean boundary conditions (Table 2). Additional information relevant to this goal is also disseminated on the WWW (see appendix) and monthly mean output data from the AMIP models are available on request from PCMDI.
The AMIP model documentation makes extensive use of the Hypertext Markup Language (HTML) to expedite the retrieval of specific information by "point-and-click" operations. This format is implemented by lists of hyperlinks that map each AMIP model to summaries of each recorded feature (Table 2). Hyperlinks also are used to cross-reference related features within a model summary and to connect reference citations to model-specific bibliographies. This feature is essential for users seeking quantitative information on model algorithms; these details are included in atmospheric modeling literature, but they are not included in the summary documentation.
Numerous tables provide a cursory overview of selected properties expressed across the AMIP models (Table 3), with hyperlinks connecting table entries to the longer summaries for each model. PCMDI plans to expand the WWW documentation as required by the ongoing demands of the AMIP. For example, over the past year about half the participating modeling centers (Table 1) have repeated the AMIP experiment with newer versions of their models, and the next phase of the intercomparison will involve additional centers.
In coming years, therefore, the WWW documentation will serve as a representative record of
AGCM development. Moreover, because the climate community increasingly uses coupled
ocean-atmosphere models as investigative tools, PCMDI will document entries to a new Coupled
Model Intercomparison Project that is coordinated by CLIVAR, the WCRP initiative for the
study of climatic variability and predictability.
Appendix
Other information pertinent to this effort such as project newsletters, data status reports, and the work of diagnostic subprojects may be accessed at http://www-pcmdi.llnl.gov/amiphome.html. Links to documentation, software, and data of general interest for climate modeling and diagnosis also are provided on PCMDI's home page at http://www-pcmdi.llnl.gov/.
Acknowledgments: We thank Rita Anderson and Michael Brösius for converting the AMIP model documentation into HTML, and representatives of the AMIP modeling groups for correcting and clarifying the documentation. This work was performed under the auspices of the U.S. Department of Energy Environmental Sciences Division at the Lawrence Livermore National Laboratory under Contract W-7405-ENG-48.
Thomas J. Phillips, Lawrence Livermore National Laboratory, Livermore, Calif.
