7. Data Land (DLND)

DLND is normally used to provide forcing data produced by a previous run using active components to drive prognostic components. Currently, there is one way of running DLND is referred to as its mode.

7.1. Supported Data Modes

DLND has its own set of supported datamode values that appears in the dlnd_in namelist input. The datamode specifies what additional operations need to be done by DLND on ALL of the streams in the dlnd.streams.xml file. Each datamode value is also associated with a DLND source file that carries out these operations and these are listed in parentheses next to the mode name.

copyall (lnd_comp_nuopc.F90)

  • This mode assumes that the data file has following variables: 1. Surface temperature (Sl_tsrf_elev) in each elevation class 2. Surface topography (Sl_topo_elev) in each elevation class 3. SMB flux (Flgl_qice_elev) in each elevation class

7.2. Configuring DLND using the CIME-CCS

If CDEPS is coupled to the CIME-CCS then the CIME $CASEROOT xml variable DLND_MODE will be generated based on the compset specification DLND%{DLND_MODE}. DLND_MODE will in term be used in the namelist_definition_dlnd.xml file to determine the collection of streams that are associated with DLND and also sets the dlnd namelist variable datamode in the file dlnd_in.

The following list describes the valid values of DLND_MODE (defined in the config_component.xml file for DLND), and how they relate to the associated input streams and the datamode namelist variable.

DLND%LCPL

  • Non-snow coupling mode. Land forcing data (produced by CLM) from a previous model run is read in from a coupler history file.

  • dlnd_mode: SCPL

  • streams: lnd.cplhist

  • datamode: copyall

DLND%SCPL

  • Snow coupling mode. Glacier coupling data (produced by CISM) from a previous model run is read in from a coupler history file.

  • dlnd_mode: LCPL

  • streams: sno.cplhist

  • datamode: copyall

In addition, the following DLND specific CIME-CCS xml variables will appear in $CASEROOT/env_run.xml:

DLND_CPLHIST_DIR

  • directory for coupler history data mode

DLND_CPLHIST_CASE

  • case name for coupler history data mode

DLND_CPLHIST_YR_START

  • starting year to loop data over

DLND_CPLHIST_YR_ALIGN

  • Simulation year corresponding to DLND_CPLHIST_YR_START (only used when DLND_MODE is CPLHIST or GLC_CPLHIST). A common usage is to set this to RUN_STARTDATE. With this setting, the forcing in the first year of the run will be the forcing of year DLND_CPLHIST_YR_START. Another use case is to align the calendar of transient forcing with the model calendar. For example, setting DLND_CPLHIST_YR_ALIGN=DLND_CPLHIST_YR_START will lead to the forcing calendar being the same as the model calendar. The forcing for a given model year would be the forcing of the same year. This would be appropriate in transient runs where the model calendar is setup to span the same year range as the forcing data.

DLND_SKIP_RESTART_READ

  • If set to true, than dlnd restarts will not be read on a continuation run.