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• Case A:  v2.LR.SSP370_0101.maint-2.0_testELMfsurdat1850

  • fsurdat = '/global/cfs/cdirs/e3sm/inputdata/lnd/clm2/surfdata_map/surfdata_ne30np4.pg2_simyr1850_2015_c211105.nc'

• Case B:  v2.LR.SSP370_0101.maint-2.0_testELMfsurdat2015

  • fsurdat = '/global/cfs/cdirs/e3sm/inputdata/lnd/clm2/surfdata_map/surfdata_ne30np4.pg2_SSP3_RCP70_simyr2015_c220420.nc' 

In Run A, fsurdat points to a file that represents land surface conditions from 1850. In Run B, fsurdat points to a file that represents land surface conditions from 2015. The same E3SM run script was used to produce Runs A & B, and all other settings between the runs were identical, including:

COMPSET="WCYCLSSP370"
RESOLUTION="ne30pg2_EC30to60E2r2"
MODEL_START_TYPE="hybrid"  # 'initial', 'continue', 'branch', 'hybrid'
START_DATE="2015-01-01"    # for SSP370 this is set automatically via the compset config
GET_REFCASE=TRUE
RUN_REFDIR="/global/cscratch1/sd/jjbenedi/ssp370/rest_for_hybrid/v2.LR.historical_0101/init/2015-01-01-00000"
RUN_REFCASE="v2.LR.historical_0101"
RUN_REFDATE="2015-01-01"   # same as MODEL_START_DATE for 'branch', can be different for 'hybrid'
do_transient_pfts = .true.
check_finidat_fsurdat_consistency = .false.
check_finidat_year_consistency = .true.
check_finidat_pct_consistency = .true.
check_dynpft_consistency = .false.
flanduse_timeseries = '/global/cfs/cdirs/e3sm/inputdata/lnd/clm2/surfdata_map/landuse.timeseries_ne30pg2_SSP3_RCP70_simyr2015-2100_c211015.nc'

Note again that Runs A & B use the same flanduse_timeseries file.

Test simulation findings

Runs A & B are not bit-for-bit (BFB) identical. BFB accuracy was expected a priori, in part because it was assumed that in a hybrid simulation, the user-provided ELM restart files would supersede those associated with the default SSP370 configuration (specifically, fsurdat as it was the only configuration change made). Between the two fsurdat files, the following variables differ:

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