GEOS-Chem restart files

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This page contains information about files produced by GEOS-Chem simulations, including diagnostic data and restart files used for initial conditions. For information the input files that ship with the GEOS-Chem run directories, please see our GEOS-Chem Input Files wiki page.

Restart files in GEOS-Chem 12

These updates were included in GEOS-Chem 12.1.0, which was released on 26 Nov 2018.

In GEOS-Chem 12.1.0, several restart file updates were introduced. These include:

Restart collection in HISTORY.rc

GEOS-Chem restart files are now saved out via the History component. A new Restart collection has been defined in HISTORY.rc and fields saved out to the restart file can be modified in that file.

New restart file names

Because we are now using the History component to archive restart files in GEOS-Chem 12.1.0 and later versions, GEOS-Chem restart file names now use this nomenclature: GEOSChem.Restart.YYYYMMDD_hhmmz.nc4.

For example, the restart file that was created at 00:00 UTC on August 1, 2016 is named: GEOSChem.Restart.20160801_0000z.nc4. The z indicates "Zulu" or "Z" time, which is another name for UTC.

New fields added to the GEOS-Chem restart file

Several new fields have been added to the GEOS-Chem restart file in an attempt to remove differences between single and multi-segmented GEOS-Chem simulations.

Item Description
1 Module-level variables H2O2s and SO2s from wetscav_mod.F have been added to State_Chm (as State_Chm%H2O2AfterChem, StateChm%SO2AfterChem). These fields will be output to the GEOS-Chem restart file and then initialized to the values saved in the restart file at the start of the next simulation. Prior to this update, both H2O2s and SO2s were initialized to the H2O2 and SO2 tracer concentrations at the start of every simulation. This change will impact multi-segmented runs only.
2 Module-level variables DRY_TOTN and WET_TOTN from get_ndep_mod.F have been added to State_Chm (as State_Chm%DryDepNitrogen, StateChm%WetDepNitrogen). These fields will be output to the GEOS-Chem restart file and then initialized to the values saved in the restart file at the start of the next simulation. Prior to this update, both variables were initialized to zero at the start of every simulation. Storing them in the restart file may improve accuracy of soil NOx emissions over multi-segmented runs. This change will impact multi-segmented runs only.
3 Move State_PSC from the HEMCO restart file to the GEOS-Chem restart file.
4 Save out instantaneous met fields TMPU1, SPHU1, PS1DRY, PS1WET, DELPDRY to the GEOS-Chem restart file. These will be used to initialize the met fields at the start of the timestep, otherwise they will be set to the values of those fields at the end of the timestep.

While this update was added to GEOS-Chem Classic in 12.1.0, it will be added to GCHP in 12.2.0.

Read restart file via HEMCO

GEOS-Chem restart files are now read in via HEMCO. The entries listed below have been added to HEMCO_Config.rc (and may vary slightly for different simulation types). These fields are obtained from HEMCO and copied to the appropriate State_Chm and State_Met fields in the new routine Get_GC_Restart (found in GeosCore/hcoi_gc_main_mod.F90).

  #==============================================================================
  # --- GEOS-Chem restart file ---
  #
  # PSC state only needed for UCX
  #==============================================================================
  (((GC_RESTART
  * SPC_           ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 SpeciesRst_?ALL?    $YYYY/$MM/$DD/$HH CS xyz 1 * - 1 1
  * TMPU1          ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Met_TMPU1           $YYYY/$MM/$DD/$HH E  xyz 1 * - 1 1
  * SPHU1          ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Met_SPHU1           $YYYY/$MM/$DD/$HH E  xyz 1 * - 1 1
  * PS1DRY         ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Met_PS1DRY          $YYYY/$MM/$DD/$HH E  xy  1 * - 1 1
  * PS1WET         ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Met_PS1WET          $YYYY/$MM/$DD/$HH E  xy  1 * - 1 1
  * DELPDRY        ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Met_DELPDRY         $YYYY/$MM/$DD/$HH E  xyz 1 * - 1 1
  * KPP_HVALUE     ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Chem_KPPHvalue      $YYYY/$MM/$DD/$HH E  xyz 1 * - 1 1
  * WETDEP_N       ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Chem_WetDepNitrogen $YYYY/$MM/$DD/$HH E  xy  1 * - 1 1
  * DRYDEP_N       ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Chem_DryDepNitrogen $YYYY/$MM/$DD/$HH E  xy  1 * - 1 1
  * SO2_AFTERCHEM  ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Chem_SO2AfterChem   $YYYY/$MM/$DD/$HH E  xyz 1 * - 1 1
  * H2O2_AFTERCHEM ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Chem_H2O2AfterChem  $YYYY/$MM/$DD/$HH E  xyz 1 * - 1 1
  (((+STATE_PSC+
  * STATE_PSC      ./GEOSChem.Restart.$YYYY$MM$DD_$HH$MNz.nc4 Chem_StatePSC       $YYYY/$MM/$DD/$HH E  xyz count       * - 1 1
  )))+STATE_PSC+
  )))GC_RESTART

The CS cycle flag was added as an option to HEMCO in GEOS-Chem 12.1.0 to tell HEMCO to skip fields that aren't found in the provided file. This is useful when certain species aren't found in the restart file and, in that case, GEOS-Chem will initialize that species to the background concentrations specified in the species database.

--Melissa Sulprizio (talk) 16:30, 7 November 2018 (UTC)

Viewing and manipulating restart files

For information on viewing and manipulating GEOS-Chem restart files in netCDF format, please see the following resources:

  1. Resources for viewing and manipulating netCDF files
  2. Regridding netCDF files
  3. Adding a new species to a restart file
  4. Working_with_netCDF_data_files#Cropping_netCDF_files#Cropping restart files to a subset of the globe

Previous issues that are now resolved

Enable compression in netCDF-4 output files

This update was included in v11-02a (approved 12 May 2017).

For more information about this issue, please see this post on our The NcdfUtilities package wiki page.

--Bob Yantosca (talk) 17:50, 24 May 2018 (UTC)

Improve write speed of netCDF output files

This update was included in GEOS-Chem v11-01 public release

For more information about this issue, please see this post on our The NcdfUtilities package wiki page.

--Bob Yantosca (talk) 19:05, 8 March 2017 (UTC)

GAMAP can now read GEOS-Chem restart files in netCDF format

This update was included in GEOS-Chem v11-01 public release

Starting in GEOS-Chem v11-01, all restart files are now saved in COARDS-compliant netCDF format. We have had to make some minor modifications to both GEOS-Chem and GAMAP in order to allow GAMAP to read these files. The table below gives a summary of these modifications.

GEOS-Chem or GAMAP? File Modification
GEOS-Chem GeosCore/gamap_mod.F In routine INIT_TRACERINFO, we now write metadata for all species (advected or not) to the tracerinfo.dat file under the ND45 tracer concentration diagnostic section. Because the netCDF restart file contains concentrations for both advected and non-advected species, we need to make sure that the tracerinfo.dat file created by GEOS-Chem contains metadata for all species.
GAMAP internals/ctm_open_file.pro The prior algorithm always assumed that a netCDF file would end in either .nc or .nc4. We now have removed this restriction. We now split the filename string on . and then examine the substrings for nc or nc4 (case-insensitive).
GAMAP internals/ctm_read_coards.pro Added some minor modifications to read netCDF restart files:
  1. Determine vertical grid from the number of layers (if the Model global attribute is not specified).
  2. Assign category DXYP to variable AREA, which is included in the netCDF restart file.
  3. Assign category IJ-AVG-$ to variables beginning with either SPC_ or TRC_. Also remove the SPC_ and TRC_ from the variable name internally so that the variable name will match the metadata in tracerinfo.dat.

--Bob Yantosca (talk) 19:29, 23 January 2017 (UTC)