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running CAM5 in CESM2.1.3

gchiodo

Gabriel Chiodo
New Member
Dear all,

I would like to use PORT to diagnose radiative forcing in CAM5. I have repeatedly tried to use PORT in the officially released CESM1.2.2 distribution, where lots of CAM5 compsets are available. Unfortunately, the PORT flag (-offline_drv rad) only works with CAM4 radiation (CAMRT) in that code distribution, but not with CAM5 radiation (RRTMG).

Recently, a few PORT compsets have been built in CESM2.x; these are the P-compsets, including one for CAM5 (PC5)

PC4 : 2000_CAM40%PORT_SLND_SICE_SOCN_SROF_SGLC_SWAV
PC5 : 2000_CAM50%PORT_SLND_SICE_SOCN_SROF_SGLC_SWAV
PC6 : 2000_CAM60%PORT_SLND_SICE_SOCN_SROF_SGLC_SWAV

I have tried to use PC5, but it needs to ingest radiation input data from a companion CAM5 experiment (i.e. the "base run"). Unfortunately, there seem to be no 'standard' CAM5 compsets available within CESM2, other than Aquaplanet experiments (e.g., the "QSC5" compset). As an example, there is no CAM5-equivalent for the FHIST and F1850 compsets. Ingesting the PC5 compset with data generated from CAM5 within CESM1.2.2 does not work either as by doing so, I am not able to reproduce the radiative fluxes of the base run. Hence, the only way to use PC5 properly is to run CAM5 in CESM2.x.... so we are back to the problem of the missing CAM5 compsets in CESM2.x.

I have tried to "revert" CAM6/CESM2.x to CAM5, by creating my own "CAM5 compset", following the CAM5 namelists generated in CESM1.2.2. However, this is a difficult task, as many BC files that are needed by CAM5 are correctly read in when using the CESM1.2.2 distribution, but not when using any CESM2.x distributions. Also, some "tuning" parameters for the CAM6 physics are different from those of CAM5.

Given these issues, I was wondering if you could consider adding some CAM5 compsets to the next CESM2.x distributions?

Users are encouraged to use CESM2 for PORT: https://bb.cgd.ucar.edu/cesm/thread...fer-software-tool-be-used-for-cesm1-2-2.5284/

However, this will only be viable if more CAM5 compsets will be added to CESM2.x. The capability of using PORT within CESM2.x to diagnose radiative forcing would be a great addition, as the "old-fashioned" stratospherically-adjusted forcing is the only way to diagnose forcings that are too small (<0.3 W/m**2) to be detected via the ERF definition.

Otherwise, is there any other way users could run CAM5 within CESM2.x?

FYI: I am currently using the CESM2.1.3, which is the latest officially released CESM2 version.

Thanks in advance for any feedback

Best regards,
Gabriel
 
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