Differences in CO2 between carbon simulation and CO2 simulation in GCClassic

[msulprizio]

Your name

Melissa Sulprizio

Your affiliation

Harvard

What happened? What did you expect to happen?

In preparation for retiring the CH4, CO2, and tagCO simulations in favor of the carbon simulation (#2387), we need to address differences that still remain between species in the carbon simulation and the standalone simulations. A 1-day simulation (Jan 1, 2019) comparison between the CO2 simulation and carbon simulation with CO2 reveals the following differences in surface CO2 concentrations.

What are the steps to reproduce the bug?

Generate the following run directories with the latest dev/14.5.0 branch (tagged at 14.5.0-alpha.11):

1. gc_4x5_merra2_CO2
2. gc_4x5_merra2_carbon_CO2
3. gc_4x5_merra2_carbon

Run each simulation for one day and compare the output.

Please attach any relevant configuration and log files.

No response

What GEOS-Chem version were you using?

14.5.0-alpha.11

What environment were you running GEOS-Chem on?

Local cluster

What compiler and version were you using?

gcc 12.2.0

Will you be addressing this bug yourself?

Yes

In what configuration were you running GEOS-Chem?

GCClassic

What simulation were you running?

Carbon

As what resolution were you running GEOS-Chem?

4x5

What meterology fields did you use?

MERRA-2

Additional information

No response

[msulprizio]

I found the SHIP logical was not defined in HEMCO_Config.rc for the carbon simulation, so ship emissions were not read in despite CEDSv2_SHIP : true. Fixing that reduced differences between the two simulations to:

There were a few other inconsistencies in HEMCO_Config.rc:

1. The DiagnFile file was not defined for the CO2 simulation so no emissions diagnostics were saved out
2. An updated version of input file Aviation_SurfCorr_SclFac.1x1.nc was used in the carbon simulation (updated for COARDS compliance and use in GCHP).

Fixing both of those did not impact the results of the CO2 simulation.

The remaining changes were able to be removed by turning off chemistry. Investigating further revealed that CO2_COPROD is true in the both simulations. I am exploring whether that source is double counted in the carbon simulation.

[msulprizio]

With the fixes now pushed to #2150, we are now able to reproduce species concentrations between the CO2 simulation and CO2-only carbon simulations.

[msulprizio]

I've changed the title of this issue to reflect that this issue tracks differences in GCClassic simulations (CO2 simulation vs CO2 in carbon simulations). GCHP differences will be tracked and fixed separately (see geoschem/GCHP#437 and geoschem/GCHP#440).

The fixes for CO2 in GCClassic carbon simulation from PR #2510 have now been merged into dev/no-diff-to-benchmark and will be included in 14.5.1.