GCHP Output Data

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  1. Hardware and Software Requirements
  2. Setting Up the GCHP Environment
  3. Downloading Source Code and Data Directories
  4. Compiling
  5. Obtaining a Run Directory
  6. Running GCHP: Basics
  7. Running GCHP: Configuration
  8. Output Data
  9. Developing GCHP
  10. Run Configuration Files

GCHP Output

List of Output Files

GCHP produces the following output data and log files:

Filename Description Notes
OutputDir/GCHP.{collection}.YYYYMMDD_HHmmz.nc4 Diagnostic output data You may customize the filename format for any collection within config file HISTORY.rc
gchp.log If adapting an example run script, this file is the primary GCHP log file. Includes all model standard output as well output from sourcing gchp.env and runConfig.sh. If using the multi-run option then this file is not produced; standard output is sent to the job log file instead per job.
HEMCO.log Log file generated by HEMCO. This file is also output when running GEOS-Chem Classic.
cap_restart MAPL output text file containing GCHP run end time. This file may be used as the next run's start time if doing multi-segmented runs. If not doing multi-segmented runs then this file should be deleted prior to rerunning so that start information in CAP.rc is used instead.
*.rcx History collection information. One file per collection.
EGRESS Empty file produced by MAPL. Can be ignored.
logfile.000000.out Log file for advection settings.
warnings_and_errors.log MAPL logging layer output. Can be ignored since GCHP does not currently use GMAO library pFlogger.

If you run GCHP using a job scheduler then you will also have a system output file.

Restart Files

GCHP restart files are called "checkpoint" files and are output to the main level of the run directory. The primary restart file is output at the end of the run and is named "gcchem_internal_checkpoint.nc" by default (see the previous chapter on configuring restart files). However, if is renamed to include 'restart' and the timestamp automatically by the sample run scripts. If you are outputting checkpoint files at regular intervals during your run then they will be output with format "gcchem_internal_checkpoint.nc.YYYYMMDD_HHmmz.bin". Despite the extension, these files are netcdf files. You may need to rename them to have the ".nc" extension for compatibility with your netcdf viewer or analysis software.

The GCHP checkpoint files contains all variables that are stored in the MAPL Internal state in GCHP and are analogous to the combined contents of the GEOS-Chem Classic and HEMCO restart files. There is one notable difference. All 3D variables in the GCHP restart file are vertically flipped. This is an important distinction to know about when comparing or preparing GCHP restart files.

Diagnostic Data

GCHP diagnostic 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_HHmmz.nc4 where one or more collection names are configured in the output configuration file HISTORY.rc. You are free to create as many additional collections with any names you choose by adding them to HISTORY.rc. You may include both 2D and 3D arrays in a single collection. However, all 3D arrays must have the same 3rd dimension size. In GCHP the 3rd dimension size is limited to # of level centers (72) and # of level edges (73).

Unlike in GEOS-Chem Classic, the contents of the HEMCO emissions diagnostic file are listed in HISTORY.rc and the output file has the same naming format as other diagnostic collections. Like the GCHP restart file, all 3D HEMCO diagnostics are flipped vertically relative to other outputs. This means the first element in the output array corresponds to top-of-atmosphere and the last element is surface. The GCPy python package includes being able to vertically flip the level dimension prior to plotting to make post-run analysis easier.

Data Visualization and Post-Processing

The GEOS-Chem python package GCPy is fully functional with GCHP output files. The same plotting functions are used for both GEOS-Chem Classic lat-lon data and GCHP cubed-sphere data, and contain the capability to automatically regrid between grid types and resolutions. Please see the GCPy GitHub page.

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