Paleoclimate ToolKit

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This documentation describes tools and procedures to guide paleoclimate scientists through the process of creating fully coupled (all active components) paleoclimate simulations using the NCAR CESM1 model release series CESM1.2. Using the CESM1 model for paleoclimate modeling requires complex, multi-step modifications to the input and forcing files used by the model, particularly for Deep Time simulations where continental configurations have changed. These tools are developed on the computing resources at the National Center for Atmospheric Research (NCAR) and we strive to keep pace with the current version of the CESM1 model. Researchers may need to modify these procedures to accommodate the version of the CESM1 model they are using, or for the computer resources available on their home machines. CESM1(CAM5/CLM4.0) is the default configuration for CESM1.2. To gain more understanding about the CESM1 component models and input files, see the CESM1 documentation.

Throughout this User's Guide we differentiate between the procedures required to create (1) near-modern (e.g., Quaternary, Pliocene) or (2) Deep-Time (pre-Quaternary) model simulations:

New Modern
In near-modern climate simulations, the continents are in their present-day positions, and the land/sea masks do not require significant modification. Quaternary modelers are often able to use existing forcing files and initial files from the pre-industrial control compset (e.g., B_1850_CN/B1850CN). This compset configures a simulation with all active components, 1850 pre-industrial forcings, with active carbon-nitrogen forcing in the CLM land model.
Deep Time
Deep time paleo climate simulations encompass time periods where the continents are in different global configurations than present day. Paleo modelers are required to provide two netCDF files with topography+bathymetry and land use (vegetation) on a regular latitude/longitude grid (e.g., 2°), using lat(lat) and lon(lon) as coordinate variables.

Additional Resources

Please look for updates on issues, including bugs, associated with this model release, on the CESM Paleoclimate sub-forum through the CESM Bulletin Board. It is the user's responsibility to keep informed of these issues.