GEOS-Chem Classic

This site provides instructions for GEOS-Chem Classic, the single-node mode of operation of the GEOS-Chem model. We provide instruction for downloading and compiling GEOS-Chem Classic, plus its required software libraries.

Note

If you would like to run GEOS-Chem on more than one node of a computing system, consider using GEOS-Chem High Performance (GCHP).

GEOS-Chem is a global 3-D model of atmospheric composition driven by assimilated meteorological observations from the Goddard Earth Observing System (GEOS) of the NASA Global Modeling and Assimilation Office. It is applied by research groups around the world to a wide range of atmospheric composition problems.

• GEOS-Chem Overview

• Narrative description of GEOS-Chem

Cloning and building from source code ensures you will have direct access to the latest available versions of GEOS-Chem Classic, provides additional compile-time options, and allows you to make your own modifications to GEOS-Chem Classic source code.

Getting Started

• Quickstart Guide
  • 1. Clone GEOS-Chem Classic
  • 2. Create a run directory
  • 3. Load your environment
  • 4. Configure your build
  • 5. Compile and install
  • 6. Configure your run directory
  • 7. Download input data
  • 8. Run your simulation
• Meet all hardware requirements
  • Computer system
  • Memory requirements
  • Disk space requirements
• Meet all software requirements
  • Supported compilers
  • Required software packages
  • Optional but recommended software packages
• Customize your login environment
  • Environment files
  • Sample environment file for GNU 12.2.0 compilers
  • Sample environment file for Intel 2023 compilers
  • Set environment variables for compilers
  • Set environment variables for parallelization
• Key references

GEOS-Chem Classic User Guide

• Download source code
  • Source code repositories
  • Download instructions
• Create a run directory
  • First-time user registration
  • Example: Create a full-chemistry simulation run directory
  • Example: Create a carbon gases simulation run directory
  • Run directory files and folders
• Compile the source code
  • Configure with CMake
  • Compile with Make
  • Get a summary of compilation options
• Configure your simulation
  • Commonly-updated configuration files
  • Less-commonly updated configuration files
• Download input data
  • Input data for GEOS-Chem Classic
  • Restart files
  • Download data with a dry-run simulation
• Run your simulation
  • Create a run script
  • Complete this pre-run checklist
  • Submit your run script to a scheduler
  • Or run the script from the command line
  • Verify a successful simulation
  • Minimize differences in multi-stage runs
  • Speed up a slow simulation
• View output files
  • Log files
  • History diagnostics output
  • Other diagnostic output files
• Diagnostics reference
  • GEOS-Chem History diagnostics
  • HEMCO diagnostics
  • Planeflight diagnostic
  • ObsPack diagnostic

Supplemental guides

• GEOS-Chem Classic folder tree
• Sample GEOS-Chem run scripts
• Load software into your environment
• Build required software with Spack
• Customize simulations with research options
• Understand what error messages mean
• Debug GEOS-Chem and HEMCO errors
• Manage a data archive with bashdatacatalog
• Archive output with the History diagnostics
• Work with netCDF files
• Prepare COARDS-compliant netCDF files
• View GEOS-Chem species properties
• Parallelize GEOS-Chem and HEMCO source code
• Run nested-grid simulations
• Update chemical mechanisms with KPP
• GEOS-Chem input data on AWS cloud
• View related documentation

Help & Reference

• GEOS-Chem version history
• Known bugs and issues
• Contributing Guidelines
• Support Guidelines
• Editing this User Guide