Legacy Instructions for Running Replay (E3SMv1)

Running the E3SM REPLAY option is a multiple phase process:

1. You need to generate the forcing from an E3SM simulation. To do this, configure your E3SM simulation with the directive "-e3smreplay" (older versions of the code used the "-camiop" directive). By default, this will generate forcing data at EVERY E3SM time step and for the entire globe and place that data in the h1 history tape. This can add up to lots of data very quickly. Therefore, if there is a particular region of the globe you are interested in, it is strongly advised that you produce forcing for a subset of the globe with the "fincl2lonlat" namelist option. You can find documentation on this namelist variable in the components/cam/bld/namelist_files/namelist_definition.xml file. Also note that you need to run with preqx version of HOMME and np4 (see the section above).

Tip: make sure add "append" when configuring with e3smreplay (i.e. ./xmlchange --id CAM_CONFIG_OPTS --append --val=’-e3smreplay’), else you may overwrite all E3SM default physics packages.

NOTE: It is advisable to NOT add any additional data to fincl2 in your namelist and make sure you are writing at the frequency you want write at. Set nhtfrq(2) = 1 to output every E3SM timestep (though you don't have to). Also, it is advised to set mfilt(2) to a large number to ensure all your forcing is in one file (else, they will have to be stitched together manually post-run).

2. If you produced forcing data for the entire globe then go directly to step 3. If you produced data for a subset of the globe then doing an ncdump -h on your .cam.h1 file you will see that E3SM appended each variable name with the latlon domain bounds, in addition to creating new dimension names. These need to be renamed before the SCM can run these. A script is provided below, which can be used to produce a file that the SCM can you. You must have nco loaded on your machine before you can run this script.

Conversion script name: E3SM_SCM_scripts/E3SM_REPLAY_rename_limitedarea.csh

3. Run the E3SM SCM with your forcing file (this will be the h1 file produced in step 1... or the file produced in step 2 if you had to rename the forcing fields). You should be using the same E3SM code tag in which you generated the forcing file from. Please use the E3SM SCM Replay script below and fill out all the required information in the USER DEFINED settings. After you build the model, you should verify that your namelist settings from your global run and SCM run are as close as possible (compare the atm_in files from the two runs). If there are significant differences, then change your namelist in your SCM REPLAY script and compile and run again.

E3SM SCM run script name: E3SM_SCM_scripts/run_e3sm_scm_REPLAY.csh

TIPS: If this is your first time running the REPLAY option it is STRONGLY advised that you test out a short simulation first. For example, run E3SM for a day or two with your output and make sure this runs in the SCM.