CPLUG 1.0 Introduction

Note: This document discusses the coupler in the CESM2.0 model although most of the contents also applies to earlier CESM versions.

How to Use This Guide

This guide covers the CESM2 top level driver implementation as well as the coupler component within the system. The driver runs on all hardware processors, runs the top level instructions, and, executes the driver time loop. The coupler is a component of the CIME infrastructure 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 and the coupler parts of the model. cpl7 code is located in the CIME source tree under driver_cpl/ and the main program of CESM2 is driver_cpl/driver/cesm_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. Coupler flow diagrams are provided in a separate document. Some additional documentation on how the coupler works can be found in Craig et al, "A New Flexible Coupler for Earth System Modeling Developed for CCSM4 and CESM1", International Journal of High Performance Computing Applications 2012 26: 31 DOI: 10.1177/1094342011428141.