CCSM3.0 Parallel Ocean Program (POP)
User Guide

A Modified Version of the POP User's Guide
Original LANL Version Information:
Version 1.4.3
February 24, 2001
Los Alamos National Laboratory

With documentation of the modifications necessary for the
Community Climate System Model (CCSM3.0 Release of POP
23 June 2004
National Center for Atmospheric Research

Brief Remarks

Manual Contents

Brief Remarks

This manual is a modified version of the official one supplied by LANL for their standard release of POP 1.4.3, with additions that are specific to the CCSM3.0 version of the POP code ("CCSM3 POP").

Topics include:

Throughout this manual, it is assumed that the operating system is some variant of Unix. However, POP will run on PCs with Windows NT using the Digital Fortran90 compiler; see Appendix 7.6 for details.

To keep the User Guide as short as possible, other manuals are provided. For the stand-alone LANL POP, the Installation Guide tells how to set up POP on any computer system that supports Fortran90 and, if it is a multi-processor system, MPI or SHMEM; for the CCSM POP, the CCSM3.0 User's Guide provides comparable information. The Scientific Desciption manual is directed toward those users who seek an in-depth understanding of the code, such as would be needed to make changes to the source code. It contains a thorough description of the code, including the model equations, their discretized form, and the numerical methods used for their solution. The principal modules and subroutines are explained, the organization of the code is outlined, and the principal variables are defined. The Code Reference manual is designed to be a reference for users who are interested in modifying CCSM POP code to suit their own research. Presently, the Code Reference contains streamlined CCSM POP calling tree and a table mapping symbols used in the Scientific Desciption manual to the corresponding variable names used in the CCSM POP code modules.

Whenever POP is run, the version number and release date of the source code on your local system is output at the beginning of the log file (see section 4.2). They should agree with the information on the front cover of this manual (compare standard-release LANL POP release stamp with the LANL version information, the CCSM stamp with the CCSM information.

If you obtained POP directly from LANL, technical support is provided by John Davis (, 505-667-4793) and Phil Jones (, 505-667-6386). If you are using POP as a component of the CCSM, the technical contact is Nancy Norton (, 303-497-1363).

We are always interested in learning about your experiences with POP, favorable or otherwise. Send your comments and suggestions for improvements to Los Alamos maintains an e-mail-driven database of bug reports at

Bug reports on problems specifically related to CCSM extensions or modifications of POP should be e-mailed to

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