CCSM4 Data Model v8: User's Guide
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Data Land Model

Modes

The land model is unique because it supports land data, runoff data, and now snow data (lnd, rof, and sno) almost as if they were three separate components, but they are in fact running in one component model through one interface. The land data is associated with the main land model. The runoff data is associated with the runoff model that runs inside the land model and is normally on a different grid than the land data. The snow data is associated with snow accumulation code (for glacial formation) inside the land model and is normally on a different grid than the land data. The snow data is new and currently unused but it's a place holder for coupling with a future land-ice component in CCSM. Each of these models, land, runoff, and snow need to have their own strdata input because they are distinct sets of fields on distinct grids with their own modes. In the data model, the land, runoff, and snow modes are treated completely independently as if there were three models.

For all three "models", land, runoff, and snow, the default science mode of the data model is the COPYALL mode. COPYALL mode will examine the fields found in all input data streams, if any input field names match the field names used internally, they are copied into the export array and passed directly to the coupler without any special user code.

Land Modes

These apply to land data associated with the main land model.

dataMode = "NULL"

NULL mode turns off the data model as a provider of land data to the coupler. The lnd_present flag will be set to false and the coupler will assume no exchange of land data to or from the data model.

dataMode = "COPYALL"

COPYALL mode copies all fields directly from the input data streams Any required fields not found on an input stream will be set to zero.

dataMode = "CPLHIST"

Same as COPYALL mode.

Runoff Modes

These apply to runoff data associated with the runoff model embedded in the land model.

dataMode = "NULL"

NULL mode turns off the data model as a provider of runoff data to the coupler. The rof_present flag will be set to false and the coupler will assume no exchange of runoff data from the data model.

dataMode = "COPYALL"

COPYALL mode copies all fields directly from the input data streams Any required fields not found on an input stream will be set to zero.

dataMode = "CPLHIST"

Same as COPYALL mode.

dataMode = "RX1"

Same as COPYALL mode.

Snow Modes

These apply to snow data associated with the snow accumulation model embedded in the land model. The snow data is new and currently unused but it's a place holder for coupling with a future land-ice component in CCSM.

dataMode = "NULL"

NULL mode turns off the data model as a provider of snow data to the coupler. The sno_present flag will be set to false and the coupler will assume no exchange of snow data to or from the data model.

dataMode = "COPYALL"

COPYALL mode copies all fields directly from the input data streams Any required fields not found on an input stream will be set to zero.

Namelist

The data land specific namelist input is as follows. The namelist input filename is hardwired in the data model code to "dlnd_in". The namelist group is called "dlnd_nml". The variable formats are character string (char), integer (int), double precision real (r8), or logical (log) or one dimensional arrays of any of those things (array of ...).

lnd_in (char)

sets the filename for the land strdata namelist. this must be set. default='unset'.

rof_in (char)

sets the filename for the runoff strdata namelist. this must be set. default='unset'.

sno_in (char)

sets the filename for the sno strdata namelist. this must be set. default='unset'.

decomp (char)

set the decomposition option for the data model. valid options are placing the global array on the root task or a simple stride-one load balanced one-dimensional decomposition. other decompositions may be added in the future. valid values are ['root','1d']. default='1d'.

restfilm (char)

restart filename for the lnd model data. this is optional. if this is unset, the restart filename will be read from the rpointer.lnd file. default='unset'.

restfilsl (char)

restart filename for the lnd stream data. this is optional. if this is unset, the restart filename will be read from the rpointer.lnd file. default='unset'.

restfilsr (char)

restart filename for the runoff stream data. this is optional. if this is unset, the restart filename will be read from the rpointer.lnd file. default='unset'.

restfilss (char)

restart filename for the sno stream data. this is optional. if this is unset, the restart filename will be read from the rpointer.lnd file. default='unset'.

The pre-defined internal field names in the data land model are as follows. In general, the stream input file should translate the input variable names into these names for use within the data land model.

Fields


     (/ "roff        ","ioff        ", &
        "t           ","tref        ","qref        ","avsdr       ","anidr       ", &
        "avsdf       ","anidf       ","snowh       ","taux        ","tauy        ", &
        "lat         ","sen         ","lwup        ","evap        ","swnet       ", &
        "lfrac       ","fv          ","ram1        ", &
        "flddst1     ","flxdst2     ","flxdst3     ","flxdst4     "  /)
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