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

Modes

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. There are several other scientific modes supported by the model, they are listed below. The mode is selected by a character string set in the strdata namelist variable dataMode.

dataMode = "NULL"

NULL mode turns off the data model as a provider of data to the coupler. The ocn_present flag will be set to false and the coupler will assume no exchange of 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 = "SSTDATA"

SSTDATA mode assumes the only field in the input stream is SST. It also assumes the SST is in Celsius and must be converted to Kelvin. All other fields are set to zero except for ocean salinity, which is set to a constant reference salinity value.

dataMode = "SOM"

SOM ("slab ocean model") mode is a prognostic mode. This mode computes a prognostic sea surface temperature and a freeze/melt potential (surface Q-flux) used by the sea ice model. This calculation requires an external SOM forcing data file that includes ocean mixed layer depths and bottom-of-the-slab Q-fluxes. Scientifically appropriate bottom-of-the-slab Q-fluxes are normally ocean resolution dependent and are derived from the ocean model output of a fully coupled CCSM run. Note that while this mode runs out of the box, the default SOM forcing file is not scientifically appropriate and is provided for testing and development purposes only. Users must create scientifically appropriate data for their particular application. A tool is available to derive valid SOM forcing. More information on creating the SOM forcing is available at: www.cesm.ucar.edu/models/ccsm4.0/data8/SOM.pdf

Namelist

The data ocean specific namelist input is as follows. The namelist input filename is hardwired in the data model code to "docn_in". The namelist group is called "docn_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 ...).

ocn_in (char)

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

restfils (char)

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

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

Fields


     (/ "ifrac       ","pslv        ","duu10n      ","taux        ","tauy        ", &
        "swnet       ","lat         ","sen         ","lwup        ","lwdn        ", &
        "melth       ","salt        ","prec        ","snow        ","rain        ", &
        "evap        ","meltw       ","roff        ","ioff        ",                &
        "t           ","u           ","v           ","dhdx        ","dhdy        ", &
        "s           ","q           ","h           ","qbot        "                 /)
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