Using CCSM3 for paleoclimate applications

This document describes the procedures for creating a CCSM3 paleoclimate simulation in the fully coupled (all active components) configuration. We provide tools and examples of the process used to create paleoclimate simulations using the computing resources at the National Center for Atmospheric Research (NCAR). This document is to be used as a guide; researchers are ultimately responsible for modifying the process to accommodate their time period of interest as well as adapting the tools to their available computer resources. 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. In near-modern 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 to simulate past climate. By contrast, deep-time simulations require drastic modifications to the land/sea mask, and the modeler is responsible for providing the orographic/bathymetric maps for their geologic period of interest. This document assumes a default fully coupled CCSM3 configuration. We do not describe the creation of the forcing files used in Data Model components or in standalone component model runs. - from Introduction p.8.