Chapter 1. CPL7 Introduction

Note: This document discusses the coupler in the CESM1 model. The coupler in this implementation is nearly identical to the version in the CCSM4 release. In fact, many of the variables, filenames, comments, and namelists still use the CCSM name convention. Any reference in this document to the CESM1 version will generally hold for the CCSM4 release as well. Comparisons are generally made to the CCSM3 coupler which was a very different coupler.

How to Use This Guide

This guide covers the CESM1 top level driver implementation as well as the coupler component within the system. The driver runs on all hardware processors and basically runs the top level instructions and executes the driver time loop. The coupler is a component of the CESM1 system that is run from within the driver. It can be run on a subset of the total processors, and carries out mapping (interpolation), merging, diagnostics, and other calculations. The name cpl7 refers to the source code associated with both the driver aspects and the coupler component aspects. cpl7 code is located in the CESM1 source tree under models/drv/ and the main program of CESM1 is models/drv/driver/ccsm_driver.F90.

This document provides a general overview of the cpl7 design. Then specific implementation issues are discussed individually. Finally, there is a section summarizing all of the cpl7 namelist input. This document is written primarily to help users understand the inputs and controls within the cpl7 system, but to also provide some background about the associated implementation.