CESM1 Paleo Users Guide


Surface datasets

If you change the land/sea mask from present day you need to create new SCRIPgrid and SCRIPmapping files in order to create a surface dataset for your simulation.  In contrast to the CCSM3 model, CESM1.x creates the surface dataset offline in a series of 3 steps.

step 1: -- make SCRIPgrid : mkmapgrids

step 2: -- make SCRIPmaps : mkmapdata

Step 3 : create new surface dataset:

for rtm:
5. rtm now requires netcdf.  We provide an IDL tool called:  rtm_ncdf.pro

Edit rtm_ncdf.pro to point to your fort.13_$CASE file (or your renamed file)

IDL> .rn rtm_ncdf                       ; compile rtm module

IDL> rtm                                   ; execute code


for CN:

1) create/spin-up clm initial condition file w/CN vars equilibrated

        RECOMMENDED procedure:
        a) run  B-case with high frequency compset and run for 30 years
        b) run   I-case with "-ad_spinup on" in CLM_CONFIG_OPTS and run
                for 600 years with finidat=‘ ‘
        c) run   I-case with “-exit_spinup on” in CLM_CONFIG_OPTS and run
                for 1 year with finidat from step 2
        d) run  I-case with neither of the above options and run for >50 years with finidat
                from Step 3.
                note: look for longterm avg NEE to be near zero for successful spinup
                      clmi from step 4 may be used for start a CNDV (dyn veg) run

        OPTIONAL procedure:
        Run without the nitrogen for a < 500-year spin-up

        a) run  B-case with high frequency compset and run for 30 years
        b) run  I-case with "-supln on" to CLM_CONFIG_OPTS and start with finidat=‘ ‘

2) create nitrogen deposition forcing file
        choices:  a) use 1850 nitdep if landmask similar enough to modern geog
                  b) run model with chemistry (jf) (expensive)
            **    c) use ncl script in cn_nitdep dir which uses zonal avgs from
                     1850 to create zonal avg for paleo. use land pts for land pts,
                     and ocean pts for ocean points. ~ procedure used for atm BAM aerosols

        do NOT: set nitdep to zero as this may cause model to compute net nit loss, WRONG