Previous Section Headers
2.3 Model Input Datasets
CAM2.0 is a combination of atmosphere, land, ocean and sea-ice
components. In what follows we discuss the input datasets required by
each of these components. CSMDATA refers to the root directory where
the distribution datasets have been untarred by the user.
2.3.1 Atmosphere Component Datasets
Input datasets needed for the atmospheric component provide initial
state data, ozone boundary data and water vapor
absorptivity/emissivity data. Only the ozone dataset contains
time-variant input data which is based on a 365 day year with no leap
years. All initial and boundary datasets are in NetCDF format.
In general input datasets following the following convention
<type><simulation date><resolution><Spectral truncation>
<Vertical levels><creation date>
Where
- Simulation date = The specific date that the given dataset is valid for. In the
case of initial condition datasets this is typically given in YYYY-MM-DD form.
Datasets that are valid over a span of dates typically list the year range.
- Resolution = Number of latitudes by the number of longitudes for the grid being used
(i.e. 64x128, 32x64 etcetera).
- Spectral truncation = For Spectral dynamical cores (eul or sld) the spectral
truncation applied to the dataset (T42, T63 etcera). This is only given if the
dataset in question has had spectral truncation applied to it.
- Vertical levels = Number of vertical levels (L26, L18 etc.)
- Creation date = The date the file was created in cYYMMDD format.
2.3.1.1 Initial Conditions Dataset
The initial conditions, dataset is specified by namelist variable
NCDATA. This dataset contains initial values of the
prognostic variables
U, V, T, Q,
PS, CWAT, TSICE, SNOWHICE
and TS1 through TS4, the surface geo-potential field
PHIS, the grid-box land fraction LANDFRAC, the land
ocean transition mask LANDM, and the standard deviation of
geo-potential height SGH. When running flux-coupled the fields:
TSICE, SNOWHICE, LANDFRAC and TS1 through TS4 are not included on the dataset.
Required initial fields are
outlined in the table below. By default, the model periodically
writes an instantaneous history file containing these fields for
possible use as initial datasets in other runs. The frequency with
which these instantaneous history datasets are written is controlled
by the namelist variable INITHIST.
Table 2.6: Atmospheric Component Initial Dataset Fields
History file
Field Name
|
Variable Name
|
Description
|
|
Multi-Level Fields
|
| T |
T |
temperature (K) |
| U |
u |
zonal wind component (m/sec) |
| V |
v |
meridional wind component (m/sec) |
| Q |
q |
water vapor specific humidity
(KgH2O/Kgair) |
| CWAT |
q(:,:,,ixcldw,:) |
cloud water mass mixing ratio
(Kgcloud/Kgair) |
|
Single Level Fields
|
| PHIS |
 |
surface geo-potential (m2/s2) |
| PS |
Ps |
surface pressure (Pa) |
| SGH |
SGH |
standard deviation of geo-potential height (m) |
| LANDM |
landm |
Land Ocean transition mask:
= 0 ocean
= 1 continent
= 0-1 transition |
| TSICE |
Tice |
CSIM sea-ice model snow/ice surface temperature (not stored on
CCSM flux-coupled simulations). |
| SNOWHICE |
|
Snow depth over ice |
| LANDFRAC |
|
Land fraction |
| TS1,TS2,TS3,TS4 |
Ts |
Four CSIM sea-ice subsurface temperature
levels (not stored on CCSM flux-coupled simulations) (K)
|
Finite-volume dynamics uses the same set of prognostic variables as
shown above, except that U and V are on a staggered grid and are
identified with names US and VS. When running with finite-volume
dynamics, the initial dataset must contain US and VS; U and V are
ignored.
All fields are instantaneous values. In addition to the
fields listed above, the initial dataset contains information on the
model date, the dimensionality of the fields,
the spectral truncation, and the latitudes, longitudes, and vertical
levels of the data.
A T42 (64 latitudes x 128 longitudes grid resolution) 26-level initial
dataset is provided with the CAM2.0 distribution:
CSMDATA/atm/cam2/inic/gaus/cami_0000-09-01_64x128_T42_L26_c020514.nc.
Other initial datasets at different model resolutions can also be
found in the directories
CSMDATA/atm/cam2/inic/gaus
and
CSMDATA/atm/cam2/inic/fv
2.3.1.2 Ozone Dataset
The ozone boundary dataset contains ozone volume mixing ratios which
are constant for a given latitude. This dataset is defined on a
pressure grid (unlike the hybrid grid of the model). These values are
interpolated to the model vertical levels at each model grid
point. The ozone dataset is in NetCDF format and contains the fields
PS and OZONE. PS is a constant 1000 mb
pressure field needed for interpolation. The ozone dataset is
specified by namelist variable BNDTVO. Unlike the initial
conditions file, CAM is capable of interpolating the ozone dataset to
any vertical and or horizontal resolution so the user need not specify
new ozone datasets when changing model resolution. The default
ozone dataset provided with the distribution is
CSMDATA/atm/cam2/ozone/noaao3.1990.21999.nc.
2.3.1.3 Water vapor absorptivity/emissivity dataset
This is a lookup table for water vapor absorption. It is specified by
setting the namelist variable, ABSEMS_DATA. The default
dataset provided with the dataset distribution can be found in
CSMDATA/atm/cam2/rad/abs_ems_factors_fastvx.052001.nc.
2.3.2 Ocean Component Datasets
The ocean component is a data ocean model which reads in input sea
surface temperature (SST) data. Running the data ocean component
requires a time-variant SST dataset. The SST dataset must be at
the model resolution and is specified by the namelist variable
BNDTVS.
The standard SST dataset is a climatological dataset containing 12
monthly time samples. The model can also read multi-year SST
datasets. If a multi-year SST dataset is used, the namelist
variable, SST_CYC must be set to .false. (it's
default value is .true.).
An SST dataset on a (64 X 128) Gaussian grid can be found in
CSMDATA/atm/cam2/sst/sst_HadOIBl_bc_64x128_clim_c020411.nc.
Other SST datasets, at different model resolutions, can also be found
in this directory.
2.3.3 Sea-Ice Component Datasets
The sea-ice component in CAM2.0 is a simplified version of the CCSM
CSIM4 code. This component requires ice coverage data. The ice
coverage data is contained in the same file as the SST data required
by the ocean component. For the standard configuration, ice-coverage
data is found in
CSMDATA/atm/cam2/sst/sst_HadOIBl_bc_64x128_clim_c020411.nc.
2.3.4 Land Component Datasets
For a full discussion of CLM2.0 input datasets see the CLM2.0 User's
Guide at
http://www.cesm.ucar.edu/models/ccsm2.0/clm/
CLM2.0 always requires a dataset providing plant functional type
physiological constants. This dataset is specified via the CLM2.0
namelist variable FPFTCON.
A time-invariant CLM2.0 surface dataset will be generated at run time
if the CLM2.0 namelist variable FSURDAT is set to blank. If
this is the case, additional settings must be provided for
MKSRF_FGLACIER, MKSRF_FLAI, MKSRF_FLANWAT,
MKSRF_FSOICOL, MKSRF_FSOITEX, MKSRF_FURBAN,
MKSRF_FVEGTYP. If a surface dataset at the model resolution
already exists, then FSURDAT should be set appropriately.
The default land surface dataset provided with the distribution is
CSMDATA/lnd/cam/srfdata/cam/clms_64x128_c020514.nc.
Other provided surface datasets at other model resolutions can also be
found in this directory.
CLM2.0 initial conditions will be generated at run time if the CLM2.0
namelist variable FINIDAT is blank (the default setting). If
spun up values exist for a model run, then FINIDAT should be
correspondingly set. The default initial dataset provided with the
distribution is:
CSMDATA/lnd/clm2/inidat/cam/clmi_0000-09-01_64x128_T42_c020514.nc.
This initial dataset should only be used in conjunction with
the default CLM2.0 surface dataset given above.
Sub Sections
-
2.3.1 Atmosphere Component Datasets
-
-
2.3.1.1 Initial Conditions Dataset
-
-
2.3.2 Ocean Component Datasets
-
-
2.3.3 Sea-Ice Component Datasets
-
-
2.3.4 Land Component Datasets
-
Search page
Questions on these pages can be sent to...
erik@ucar.edu .
$Name: $ $Revision: 1.1 $ $Date: 2004/06/08 02:57:21 $ $Author: jmccaa $