User's Guide to NCAR CCM0B

This document describes the general program design and data organization of the version of NCAR Community Climate Model designated CCMOB. The basic adiabatic model was acquired from the European Centre for Medium Range Weather Forecasts in Reading, England, in February 1981. Changes have been made to the model in operational aspects, in the numerical approximations and in treatment of physical parameterizations. However, the basic code structure is, for the most part, unchanged. This document is intended to provide a description of the basic model structure and data organization in enough detail that a user can begin to add to or modify the code for his own research. Section II first presents a general description of the model flow (Figure 2.1), then gives additional detail, first in brief word description form (Figure 2.2) followed by detailed flow diagrams (Figures 2.3-2.7). Section III describes the data organization of the model, including the data buffer structures and the data flow of the model. Section IV describes a typical model run. It explains the job control language (JCL), datasets local to the job, input control parameters, required initial data, normal output from the model, and the save/restart process for continuing model runs or recovering from abnormal terminations. Section V explains steps for adding new variables to the model buffers and gives examples of such changes. It also discusses modifications needed to change model resolution. This report, along with a report describing individual subroutines of the model (Williamson et al., 1983), and a report describing the model equations, physical parameterizations, and computational aspects (Williamson, 1983) are intended to provide sufficient documentation to allow users to understand, modify and use the model.