User's Guide to NCAR CCM3.6 Search Page

2. Using CCM3.6

2.2 Model Input Variables

The CCMEXP namelist control variables are broken into the following categories:

• Define the type and length of run
• Input datasets
• File  archive control
• History file options
• Restart file options
• Model time
• Physics controls
• Non-water constituents
• Memory controls
• Orbital parameters

• Variable name.
• Variable type (Character, Integer, Real, or Logical). If the variable is of type character, then its declared length is displayed along with the variable type (e.g. CTITLE is 80 characters in length, therefore C*80 is entered in the "Type" column).
• Default variable value.
• Examples from Sec. 2.4  demonstrating usage.
• Variable description

 

Table 2.5: CCMEXP namelist Input Variables

Variable Name	Type	Default  Value	See	Description
Define the type and length of run
CASEID	C*8	Blanks	Ex.1	Case identifier. Saved in history file header record (refer to Table 3.1 ), and used as part of the MSS path name (see Sec. 2.5.3).
CTITLE	C*80	blanks	Ex.1	Case title.
NELAPSE	I	-999999999	Ex.3	Elapsed time in iterations (positive) or days (negative) to run. May be input instead of NESTEP.*  REQUIRED if NESTEP not set.
NESTEP	I	-999999999	Ex.1	If positive the ending absolute timestep (from the start of the initial run). Or if negative the ending absolute (from the start of the initial run) number of days to process. .*  REQUIRED if NELAPSE not set.
NSREST	I	0	Ex.1   Ex.3   Ex.5	Run type:  0=initial  1=restart  3=branch   (option 2 no longer exists)
*No usable default value exists for this variable. One of NESTEP or NELAPSE is required to be set. If both are set, then the value of NESTEP will override the value of NELAPSE.
Input datasets
BNDTVO	C*80	blanks	Ex.1   Ex.2	Full pathname or filename of time-variant, ozone mixing ratio's boundary dataset (netCDF format).  REQUIRED
BNDTVS	C*80	blanks	Ex.1   Ex.2   Ex.7	Full pathname or filename of time-variant, sea-surface temperature's boundary dataset (netCDF format).  REQUIRED
DATADIR	C*80	'.'		Directory where input datasets may be found
NCDATA	C*80	blanks	Ex.1   Ex.2   Ex.7	Full pathname or filename of initial dataset (netCDF format).  REQUIRED for initial run (NSREST=0).
OZNCYC	L	.TRUE.		Flag for yearly cycling ozone dataset. If .FALSE., assume multiyear dataset.
SSTCYC	L	.TRUE.	Ex.7	Flag for yearly cycling SST dataset. If .FALSE., assume multiyear dataset.
Mass Store controls
IRT	I	99999	Ex.1   Ex.2   Ex.6   Ex.9	Retention period in days for history files stored on Mass Store. If IRT=0, no history or restart files will be archived.
NSWRPS	C*8	blanks	Ex.1   Ex.5	Mass Store, write password, for all output datasets. Must remain the same throughout a case, or a continuation run will not update original history files.
RIRT	I	99999	Ex.6	Retention period for Mass Store restart files. Same defaults and maximums as IRT.  If RIRT=0, then no restart files will be archived.
History file options
AUXF  (pflds*   (ptapes-1))	C*8	blanks	Ex.5   Ex.8	Input array used to define the fields to be output on up to 5 auxiliary history files; see Sec. 2.5.
CPUCHEK	L	.FALSE.		If set, check after each history file write, to determine if there is sufficient CPU time remaining, to do another history file write. If there is not, stop.
EXCLUDE  (pflds)	C*8	blanks	Ex.5	List of fields to exclude from the primary history file (these fields would otherwise appear by default on the primary history file; see Sec. 2.5).
INITHIST	C*16	'MONTHLY'		Generate initial dataset as auxiliary history file (see Sec. 2.5.1.3). Can be set to 'MONTHLY' , 'YEARLY', or 'NONE'. If set to 'NONE' then initial datasets will not be created.  The  files are named by the date as follows ccmi_yyyymmdd_sssss.  Where, yyyy refers to the year, mm to the month, dd to the day, and sssss to the seconds within the day. The resulting files must be converted into netCDF format before using as initial conditions.
MFILT  (ptapes)	I	5,5,5,...	Ex.1   Ex.5   Ex.9	Array of number of time samples to write to the primary and auxiliary history files (a time sample is the history output from a given timestep; several time samples can fit on one  file).
NDENS  (ptapes)	I	1,1,1,...	Ex.1   Ex.5   Ex.9	Array specifying packing densities (1,2 or 4) for primary and auxiliary history files. NDENS is only valid on an NCAR Cray. (see CRAYLIB documentation)
NHTFRQ  (ptapes)	I	-24,0,0,..	Ex.1   Ex.5   Ex.9	Array of time sample, write frequencies, for primary and auxiliary history files.  If NHTFRQ(i)=0, no file will be written.  If NHTFRQ(i)>0, frequency is input as number of timesteps.  If NHTFRQ(i)<0, frequency is input as number of hours.
NINAVG  (ptapes)	C*1	'A','A',...	Ex.5   Ex.6   Ex.8	Array of field type flags for primary and auxiliary history files:  'A'= averaged over nhtfrq(i)  'I'= instantaneous  'M'= point minimum over nhtfrq(i)  'X'= point maximum over nhtfrq(i)  'Q'= monthly-averaged; applies only to the primary history file. All fields on a history file are of the type indicated by ninavg(i) except variables ORO and PHIS. ORO and PHIS are always instantaneous.
NLFILT	L	.FALSE.		Flag to put one extra time sample on the first history file of current case. This aids in bookkeeping of long runs.
PRIMARY  (pflds)	C*8	blanks	Ex.6	List of fields to include in primary history file (must be in Master Field List; these fields do not appear by default on the primary history file; see Sec. 2.5).
STFNUM	I	1		Start history file and restart file naming with this number (min=1; max=9999).
Restart file options
MXSZRG	I	2**30		Maximum size allowed for restart dataset . If MXSZRG< 106 units are megabytes, otherwise in bytes.
NREFRQ	I	1		Frequency of restart dataset writes.  This variable can only be 1 or 0.  If 1, restart files are written and archived for every archive of the primary history file. If this variable is 0, then no restarts are written.
NREVSN	C*72	blanks	Ex.5	Full pathname of master restart file from which to branch.  REQUIRED for branch run.
REST_PFILE	C*80	blanks		Full pathname of restart pointer file.
Model time
DTIME	R	1200.	Ex.1	Length of model timestep in seconds. CAUTION: Changing this variable directly impacts the physical parameterizations in the model and may impact the climate. Changing resolution usually requires a change in DTIME.
NNBDAT	I	-9999	Ex.1   Ex.7	Base date for run as yyyymmdd. If not input, set to NCDATE from initial dataset header.
NNBSEC	I	-9999	Ex.1   Ex.7	Seconds of base date. If not input, set to NCSEC from initial dataset header.
NNDBAS	I	-9999	Ex.1	Base model day for run. If not input, set to NDCUR from initial dataset header.
NNSBAS	I	-9999	Ex.1	Seconds of base model day for run. If not input, set to NSCUR from initial dataset header.
Physics controls
ADIABATIC	L	.FALSE.		If true, do not run model physics. Run only the dynamical core (in this mode, water vapor is advected as a passive tracer).
CO2VMR	R	3.550e-4	Ex.4	CO2 volume mixing ratio.
CH4VMR	R	1.714e-6	Ex.4	CH4 volume mixing ratio.
N2OVMR	R	0.311e-6	Ex.4	N2O volume mixing ratio.
F11VMR	R	0.280e-9	Ex.4	CFC11 volume mixing ratio.
F12VMR	R	0.503e-9	Ex.4	CFC12 volume mixing ratio.
DIF2	R	2.5E5 *		del2 horizontal diffusion coefficient.
DIF4	R	1.E16 *		del4 horizontal diffusion coefficient.
DIVDAMPN	R	0.0		Number of days (from nstep 0) to run divergence damper. Use only if model is blowing up because of spin-up problems. Suggested value: 10.
EPS	R	0.06 *		Time filter coefficient.
FLXAVE	L	.TRUE.		If true, only send data to the flux coupler on radiation time steps. This namelist variable only relevant for flux-coupled runs.
IDEALDYN	L	.FALSE.		If true, only the dynamical core of the model is run. The model physics is replaced by an "idealized physics" routine which specifies an analytic heating profile and damping of low level winds. Water vapor is set  to 0 everywhere.  Phis is set to 0 everywhere. See Held & Suarez (1994) for more details.
IRADAE	I	-12		Frequency of absorptivity/emissivity calculations in iterations (if positive) or model hours (if negative). To avoid having the abs/ems values saved on the restart output, this variable should divide evenly into MFILT(1)*NHTFRQ(1).
IRADLW	I	-1		Frequency of long-wave radiation calculation in timesteps (if positive) or model hours (if negative).
IRADSW	I	-1		Frequency of short-wave radiation calculation in timesteps (if positive) or model hours (if negative).
ITSST	I	1		Frequency of SST update in timesteps.
KMXHDC	I	1		Number of levels over which to apply Courant limiter, starting at top of model.
NLVDRY	I	3		Number of layers from the top of the model over which to do dry convective adjustment. Must be less than plev (the number of vertical levels).
PERTLIM	R	0.		Maximum size of perturbation to apply to initial temperature field (set non-zero for, numerics testing purposes only).
SCON	R	1.367E6	Ex.4	Solar constant.
TAUVIS	R	0.14		Visible optical depth.
* Appropriate for the T42/18-level  resolution
Non-water constituents
NUSR_ADV	I	0		number of user defined advected tracers
NUSR_NAD	I	0		number of user defined non-advected tracers
READTRACE	L	.TRUE.		If true and PCNST+PNATS .GT. 1, obtain all initial tracer data from initial conditions dataset.
TRACE_TEST1     TRACE_TEST2     TRACE_TEST3	L     L     L	.FALSE.     .FALSE.     .FALSE.		If true, turn on test tracer code with 1 tracer (PCNST=2).  If true, turn on test tracer code with 2 tracers(PCNST=3).  If true, turn on test tracer code with 3 tracers(PCNST=4).  NOTE: For testing/debugging purposes only. Leave FALSE during production runs.
Memory controls
INCORBUF	L	.TRUE.	Ex.1	If true, then keep main model buffers in-core (buffers b1 and b2).
INCORHST	L	.TRUE.	Ex.1	If true, then keep the history buffer in-core.
INCORRAD	L	.TRUE.	Ex.1	If true, then keep abs/ems buffer in-core.
LINEBUF	L	.FALSE.	Ex.9	If true, force buffer flush of stdout with each new-line generated (useful for debugging).
Orbital parameters
ECCEN	R	UNDEFINED	Ex.4	Earth's eccentricity of orbit.  (unit-less: typically 0. to 0.1).  REQUIRED
IYEAR_AD	I	UNDEFINED	Ex.1   Ex.4	Year (AD) used to compute earth's orbital parameters. If not set, then use the values from the eccen, mvelp, and obliq namelist parameters.  REQUIRED
MVELP	R	UNDEFINED	Ex.4	Earth's moving vernal equinox at perihelion (degrees: 0. to 360.0).  REQUIRED
OBLIQ	R	UNDEFINED	Ex.4	Earth's orbital  angle of obliquity  (degrees: -90. to +90., typically 22. to 26.).  REQUIRED
If only IYEAR_AD is set, orbital parameters will be computed automatically (based on Berger, 1977).   If one of  OBLIQ, ECCEN, OR MVELP is set, all three must be set.   If all four of the above are set by the user, IYEAR_AD takes precedence.

 

The namelist LSMEXP is used to set variables that control the LSM portion of the model.  Namelist variables are preset and read by routine lsmctli. Table 2.6 displays the LSMEXP variables.  Note that several LSMEXP namelist variables are identical to and superceded by those in the CCMEXP namelist when CCM3.6 is run as a stand-alone model. These variables can only have values different from CCM3.6 when the LSM model is run through the flux coupler. Hence, they are not repeated in Table 2.6.
 

Table 2.6: LSMEXP namelist Input Variables

Variable Name	Type	Default  Value	See	Description
ANTARTICA	L	.TRUE.		If true, extend Antarctica for Ross Ice Shelf glacier.  Only used when FINIDAT is set to "arbitrary initialization"
CHNTYP  (2,malflds)	C*8	Blanks		Paired 8-character field name and field type. Overrides, default settings.
CTITLE	C*80	Blanks	Ex.1	Case title.
DATADIR	C*80	'.'		Directory where input datasets reside.
EXCL  (malflds)	C*8	Blanks		Names of fields to exclude from history file.
FINIDAT	C*80	'not_specified'	Ex.1   Ex.7	Initial conditions filename.  REQUIRED for initial run.
FLDS1D  (malflds)	C*8	Blanks		Names of fields to output as 1-dimensional to history file.
FLXAVE	L	.TRUE.		If true, only communicate with the flux coupler on time steps where albedos are calculated.
HYDRO	L	.TRUE.		Used prognostic hydrology if true.
LOCPNH	C*80	'.'		Directory where output history files are written.
LOCPNR	C*80	'.'		Directory where output restart files are written.
NREVSN	C*80	blanks		Full restart pathname for branch run.  REQUIRED for branch run.
NSWRPS	C*8	blanks		Mass store, write password, for output files.
PERGRO	L	.FALSE.		Flag for random perturbation test. Set TRUE for numerics testing purposes only. Otherwise leave FALSE.
REST_PFILE	C*80	'~/lnd.CASEID.rpointer'		Full UNIX pathname of restart pointer file.

 

The model is capable of executing using default values for most of the namelist variables (most default values are only appropriate at the T42/18-level resolution). However, some of the namelist variables must be explicitly set by the user in order for the model to run. CCMEXP variables that must be set are CASEID, NESTEP (or NELAPSE), NCDATA, BNDTVS, BNDTVO, and some combination of the orbital parameters (IYEAR_AD, or MVELP, ECCEN, and OBLIQ) as discussed at the bottom of Table 2.5.   The only required LSMEXP variable is FINIDAT.
 

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