Add checklist as per ESCOMP#1309

README.CHECKLIST.new_case

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+$CTSMROOT/README.CHECKLIST.new_case                       03/01/2021
+
+This is a check list of things to do when setting up a new case in order to help ensure everything is correct. There
+are lots of tiny details that need to be right and it's easy to get something wrong. So the first screening to make
+sure it's right is for you to carefully check through your case and make sure it's right.
+
+The following assumes you have created a new case and are in it's case directory.
+
+General Checklist to always do:
+
+ - Make sure CLM_ env settings are correct 
+   (./xmlquery -p CLM)
+ - Make sure you are using the correct CLM_PHYSICS_VERSION
+   (./xmlquery -p CLM_PHYSICS_VERSION)
+ - Make sure you are running the appropriate overall CLM vegetation model. 
+   The "-bgc" option of either Satellite Phenology (sp), or
+   Full BioGeoChemistry (bgc), or FATES (fates)
+   (./xmlquery -p CLM_BLDNML_OPTS)
+ - Also if you are running the bgc model, check to see if you should be running the prognostic crop model 
+   (option -crop in CLM_BLDNML_OPTS)
+ - Make sure the LND_TUNING_MODE is correct 
+   (./xmlquery LND_TUNING_MODE)
+ - For an "I compset" make sure you are running over the right forcing years 
+   (usually ./xmlquery -p DATM_CLMNCEP_YR)
+ - First and align year for streams should be the start year of a historical simulation 
+   (./xmlquery RUN_STARTDATE)
+   (grep stream_year_first CaseDocs/lnd_in; grep model_year_align CaseDocs/lnd_in)
+ - Last year for streams should be the last year you are going to run to (or beyond it) 
+   (grep stream_year_last CaseDocs/lnd_in)
+ - Make sure you are starting from appropriate spunup initial conditions 
+   (Check the run-type with: ./xmlquery RUN_TYPE)
+   (check finidat for a startup or hybrid simulation: grep finidat CaseDocs/lnd_in)
+   (check nrevsn for a branch simulation: grep nrevsn CaseDocs/lnd_in)
+ - Run for a month (or some short period) and go over the log files and especially the settings and files read in them.
+   (For an I case you especially want to look at the lnd.log and atm.log files)
+
+Some other suggestions on things that can be done:
+
+- Compare namelist files to an existing case if you are doing something almost the same as a previous simulation.
+- Ask another collaborator to look over your case directory