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There is not a compset for the MOSAIC scheme so you must make the changes listed below.

Create new case

After creating a new case in the usual way, issue the following commands in your new case directory (for running on Derecho):

./xmlchange PIO_STRIDE=1
./xmlchange NTASKS=2048
./case.setup

Change env_build.xml

Once you set up your case from the code through create_newcase, you You need to change a few files to use MOSAIC. 

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Replace "MOSAIC_MECH_FILE" to your file path. The mechanism file is available to download herewith the full path to the MOSAIC mechanism file, which you can download here and copy to Derecho (or your HPC): MZ272_TS1.1_simpleVBS_MOSAIC_20210528.in

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• The current CAM-chem/MOSAIC was implemented in CAM6.3.018, which is similar to the CESM2.2 public version but with some minor updates made to CAM. 
• We have only used it using the "FCnudged" compset. No other compsets have been tested yet. FHIST compset will not work. 
• You should use "MAM4" to use MOSAIC at this moment, since some parts of the code were hard coded to MAM4 (MAM3 and MAM7 are not compatible with MOSAIC). We are hoping that it can be more flexible in the future when MOSAIC is available in the default version.

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