GCHP Output Data

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  1. Downloading Source Code
  2. Obtaining a Run Directory
  3. Setting Up the GCHP Environment
  4. Compiling
  5. Basic Example Run
  6. Run Configuration Files
  7. Advanced Run Examples
  8. Output Data
  9. Developing GCHP

Output Files

Running GCHP produces several output data and log files. The table belows lists what files to expect. All of these files are deleted if you run make cleanup_output within the run directory. Note that you must delete cap_restart prior to rerunning after recompiling or you will run into a segmentation fault as documented on the Troubleshooting GCHP wiki page.

Filename Description
OutputDir/GCHP.center.YYYYMMDD.nc4 Cubed sphere output data
GCHP.log Log file containing GCHP standard output such as is generated by files in MAPL source code in directory GCHP/Shared. Note that you can change this log file's name when you run GCHP. GCHP.log is the default name used in the sample run scripts and in examples in this user guide.
PET00000.EOSCHEMchem.log Log file containing GEOS-Chem standard output such as is generated by files in source code directory GeosCore. This file does not contain output generated by code in the GCHP source code directory.
HEMCO.log Log file generated by HEMCO. This file is also output when running GEOS-Chem classic.
cap_restart Text file either generated on the fly by MAPL if one does not already exist or is output by a previous GCHP run. Its contents replace the simulation start and end time information in input.geos. Unless doing multi-segmneted runs, this file should be deleted before starting a new run so that MAPL creates a new file with the start and duration information stored in CAP.rc. If an old cap_restart is present, simulation time information in that file will be used even if different from CAP.rc.
regrid.rcx, center.rcx Can be ignored.
EGRESS Can be ignored.
trac_avg.gchp_c24_standard.YYYYMMDDHHmm This file is a vestige of GEOS-Chem classic code. It can be ignored. All GCHP data output is in the OutputDir subdirectory. Diagnostics are not currently output.

Data Visualization and Post-Processing

GCHP output data is in netCDF-4 format and is stored in the OutputDir directory within your run directory. The output filename format is GCHP.collection.YYYYMMDD.nc4 where one or more collection names are configured in the output configuration file HISTORY.rc. The default collection is "center". You are free to create as many additional collections with any names you choose. Be aware that the vertical axis in GCHP output data is flipped relative to GEOS-Chem classic, with the lowest level index corresponding to the top of atmosphere.

Each collection is on the cubed-sphere grid at the resolution of your run. You can conservatively regrid to lat-lon for post-run analysis using one of the tools described below.

We currently recommend that you the FORTRAN tool CSRegridTool developed by Sebastian Eastham (MIT) for regridding GCHP output data to lat-lon. This package is available at https://bitbucket.org/sdeastham/csregridtool.

You may also use the CSGrid Matlab package, also developed by Sebastian Eastham (MIT) and which contains an extensive library for post-processing and data visualization of both cubed sphere and lat-long grids. This package is available at https://bitbucket.org/gcst/csgrid.

Please note that the development of python tools for GCHP regridding and data analysis is currently in progress. This python suite will replace the IDL-based GAMAP software used with GEOS-Chem "classic". If you are interested in helping out with this project, please contact the GEOS-Chem Support Team.

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