User's Guide to NCAR CAM2.0

2. Using CAM2.0

    2.4 Example Namelists

2.4.2 Example 2 -- T21 One Day Initial Run

 % setenv CSMDATA /data
 % build-namelist -case run02 -namelist "&camexp start_ymd=010901 \
    start_tod=0 stop_ymd=010902 stop_tod=0 mss_irt=0 /"

To utilize this namelist, the model must be configured to run at T21 resolution. This namelist does not provides a CLM2.0 initial dataset at T21. When an initial dataset is not specified, CLM2.0 will generate 'reasonable values' for certain model variables as part of its initialization. When running without specifying an initial CLM2.0 dataset, the model should be run for several years in order for the land-component to "spin-up". During a model run, CLM2.0 will generate initial datasets either monthly or yearly depending on the setting of the clmexp variable, HIST_CRTINIC. These initial datasets can then be used to obtain "spun-up" initial states for future T21 runs.

 &camexp
 caseid = 'run02'
 absems_data = '/data/atm/cam2/rad/abs_ems_factors_fastvx.052001.nc'
 ncdata = '/data/atm/cam2/inic/gaus/cami_0000-09-01_32x64_L26_c020514.nc'
 bndtvs = '/data/atm/cam2/sst/sst_HadOIBl_bc_32x64_clim.c020426.nc'
 bndtvo = '/data/atm/cam2/ozone/noaao3.1990.21999.nc'
 dtime = 1800
 dif2 = 2.5E5.
 dif4 = 2.0E16.
 nsrest = 0
 start_ymd = 010901
 start_tod = 0
 stop_ymd = 010902
 stop_tod = 0
 iyear_ad = 1950
 mss_irt = 0
 reset_csim_iceprops = .true.
 /

 &clmexp
 fpftcon = '/data/lnd/clm2/pftdata/pft-physiology'
 fsurdat = '/data/lnd/clm2/srfdata/cam/clms_32x64_c020515.nc
 /

NCDATA

Specifies the T21 initial conditions dataset.

BNDTVO

The default ozone dataset can be used with any spatial resolution. The model will interpolate the dataset to the correct resolution.

BNDTVS

Specifies the T21 SST dataset.

DTIME

Specifies the appropriate timestep (1800 seconds) to use at T21.

DIF2

Specifies the appropriate value of the del2 horizontal diffusion coefficient to use at T21.

DIF2

Specifies the appropriate value of the del4 horizontal diffusion coefficient to use at T21.

START_YMD

Specifies the starting year, month and day of the model run.  

START_TOD

Specifies the starting time of day of the model run.  

STOP_YMD

Specifies the ending year, month and day for the model run.   The above namelist results in a run which will end after one day. 

STOP_TOD

Specifies the stopping time of day for the model run.   These namelist settings results in a run which will end after one day. 
Hint: When starting a long run, it is a good idea to make a 1-day initial run, then restart the case for the remainder of the experiment.  If the system crashes and the job is rerun,  the model will restart from the last restart files.  If on the other hand, you specified your model run as one long, initial run,  the job would reload the initial namelist and start again from the beginning, duplicating all model results from the aborted job.

MSS_IRT

No history files or restart files will be archived. If there is no connection to an archival device, MSS_IRT should be set to zero and output datasets will be written to disk.  If this variable is non-zero, the model will build an archival command that it will execute as a shell command.

RESET_CSIM_ICEPROPS

Reset the state variables of the CSIM sea-ice model. Sometimes this is needed to get the sea-ice model to start-up when the initial conditions dataset is not in equilibrium. Typically, this is needed when the initial conditions dataset used for the simulation was not a spun-up state output from the model, but either interpolated from another dataset or from an outside source such as empirical data.

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Questions on these pages can be sent to... erik@ucar.edu .