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User's Guide to NCAR CAM2.0


2. Using CAM2.0

    2.4 Example Namelists

2.4.4 Example 4 -- T42 Paleo run

This namelist generates an initial run beginning on September 1, 4050 BC (6000 BP) and continuing for one day.  The earth's orbit, solar constant, and the volume mixing ratio for the greenhouse gases are defined in the namelist since these values change for a paleo-climate simulation. To obtain this namelist, the user may invoke build-namelist with command line arguments. However, since the number of command line arguments for this case are numerous, an easier solution is for the user to first create a namelist file, namelist_input, with the following contents:

 &camexp
 caseid = 'run04'
 ctitle = 'Paleo-climate run: 4050 BC'
 eccen = 0.01868126
 obliq = 24.10538
 mvelp = 0.87
 co2vmr = 2.80e-4
 ch4vmr = 0.700e-6
 n2ovmr = 0.275e-6
 f11vmr = 0.
 f12vmr = 0.
 scon = 1.363e6
 /

The user may then invoke build-namelist as follows: 


 % setenv CSMDATA /data
 % build-namelist -infile namelist_input

The user should invoke this command from the same directory from which configure was invoked.

 &camexp
 caseid = 'run04'
 ctitle = 'Paleo-climate run: 4050 BC'
 absems_data = '/data/atm/cam2/rad/abs_ems_factors_fastvx.052001.nc'
 ncdata = '/data/atm/cam2/inic/gaus/cami_0000-09-01_64x128_T42_L26_c020514.nc'
 bndtvs = '/data/atm/cam2/sst/sst_HadOIBl_bc_64x128_clim_c020411.nc'
 bndtvo = '/data/atm/cam2/ozone/noaao3.1990.21999.nc'
 nsrest = 0
 nelapse= -1
 eccen = 0.01868126
 obliq = 24.10538
 mvelp = 0.87
 co2vmr = 2.80e-4
 ch4vmr = 0.700e-6
 n2ovmr = 0.275e-6
 f11vmr = 0.
 f12vmr = 0.
 scon = 1.363e6
 /

 &clmexp
 fpftcon = '/data/lnd/clm2/pftdata/pft-physiology'
 fsurdat = '/data/lnd/clm2/srfdata/cam/clms_64x128_c020514.nc'
 finidat = '/data/lnd/clm2/inidata/cam/clmi_0000-09-01_64x128_T42_c020514.nc'
 /

ECCEN,  OBLIQ,  MVELP

Sets the earth's orbital parameters for year 4050 BC.  For the most accuracy,  the parameters ECCEN,  OBLIQ,  and MVELP  should be set rather than calculated based on IYEAR_AD.   If IYEAR_AD is specified, the other orbital namelist parameters are ignored. If the user wants to calculate the orbital parameters for 4050 BC using (Berger, 1977) the values for   for ECCEN, OBLIQ, and MVELP should be omitted and only IYEAR_AD should be specified as IYEAR_AD = -4050

CO2VMR, CH4VMR, N2OVMR, F11VMR, F12VMR

Sets the volume mixing ratios for the greenhouse gases: CO2, CH4, N2O, CFC11, and CFC12. The values are set to values that might be reasonable for 4050 BC.

SCON

Set the solar constant to 1363 W/m2.

BNDTVO, BNDTVS, NCDATA, FSURDAT, FINIDAT

In this example these datasets would not be appropriate for a paleo run. In general, the user will want to create their own datasets. In particular, the atmospheric initial conditions dataset and the CLM2.0 surface and initial datasets all contain a land mask field which is normally modified for a paleo run.

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$Name: $ $Revision: 1.1 $ $Date: 2004/06/08 02:57:22 $ $Author: jmccaa $