4. Data Atmosphere (DATM)

DATM is normally used to provide observational forcing data (or forcing data produced by a previous run using active components) to drive prognostic components. The various ways of running DATM is referred to as its mode.

In the case of CESM, the active model components would be: CTSM, POP2, MOM6, POP2, CICE5-6, WW3 and MOSART. As examples, CORE2_NYF (CORE2 normal year forcing) is the DATM mode used in driving POP2 and MOM6. On the other hand CLM_QIAN, CLMCRUNCEP, CLMGSWP3 and CLM1PT are DATM modes using observational data for forcing CTSM.

4.1. Supported Data Modes

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

CLMNCEP (datm_datamode_clmncep_mod.F90)

  • In conjunction with NCEP climatological atmosphere data, provides the atmosphere forcing favored by the CESM Land Model Working Group when coupling an active land model with observed atmospheric forcing. This mode replicates code previously found in CLM (circa 2005), before the LMWG started using the CIME coupling infrastructure and data models to do active-land-only simulations.

CORE2_NYF (datm_datamode_core2_mod.F90)

  • Coordinated Ocean-ice Reference Experiments (CORE) Version 2 Normalst_aquap[1-10]Year Forcing.

CORE2_IAF (datm_datamode_core2_mod.F90)

  • In conjunction with CORE Version 2 atmospheric forcing data, provides the atmosphere forcing when coupling an active ocean model with observed atmospheric forcing. This mode and associated data sets implement the CORE-IAF Version 2 forcing data, as developed by Large and Yeager (2008) at NCAR. Note that CORE2_NYF and CORE2_IAF work exactly the same way.

CORE_IAF_JRA (datm_datamode_jra_mod.F90)

  • In conjunction with JRA-55 Project, provides the atmosphere forcing when coupling an active ocean model with observed atmospheric forcing. This mode and associated data sets implement the JRA-55 v1.3 forcing data.

ERA5 (datm_datamode_era5_mod.F90)

  • Fifth generation ECMWF atmospheric reanalysis of the global climate. This mode is mainly used by NOAA’s UFS Weather model to support different applications such as HYCOM ocean and NOAHMP land components.

Note

Due to the high temporal and spatial resoultion of ERA5 dataset, only 2019 data is staged on NCAR’s Cheyenne platform under $CESMDATAROOT/inputdata/atm/datm7/ERA5

Note

In addition to the exiting DATM data modes, the CDEPS fork used by NOAA’s UFS Weather Model also includes additional data modes such as CFSR, GEFS and GFS. These data modes are not merged with the NCAR’s authoritative repository yet but it is tested under UFS Weather model.

4.2. Configuring DATM from CIME

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

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

DATM%CORE2_NYF,

  • CORE2 normal year forcing (CESM C ang G compsets)

  • datm_mode: CORE2_NYF

  • streams: CORE2_NYF.GISS,CORE2_NYF.GXGXS,CORE2_NYF.NCEP

  • datamode: CORE2_NYF

DATM%CORE2_IAF,

  • CORE2 interannual year forcing (CESM C ang G compsets)

  • datm_mode: CORE2_IAF

  • streams: CORE2_IAF.GCGCS.PREC,CORE2_IAF.GISS.LWDN, CORE2_IAF.GISS.SWDN,CORE2_IAF.GISS.SWUP, CORE2_IAF.NCEP.DN10,CORE2_IAF.NCEP.Q_10, CORE2_IAF.NCEP.SLP_,CORE2_IAF.NCEP.T_10,CORE2_IAF.NCEP.U_10, CORE2_IAF.NCEP.V_10,CORE2_IAF.CORE2.ArcFactor

  • datamode: CORE2_IAF

DATM%CORE_IAF_JRA

  • JRA-55 intra-annual year forcing (CESM C ang G compsets)

  • streams: CORE_IAF_JRA.PREC,CORE_IAF_JRA.LWDN,CORE_IAF_JRA.SWDN, CORE_IAF_JRA.Q_10,CORE_IAF_JRA.SLP_,CORE_IAF_JRA.T_10,CORE_IAF_JRA.U_10, CORE_IAF_JRA.V_10,CORE_IAF_JRA.CORE2.ArcFactor

  • datamode: CORE_IAF_JRA

DATM%CLM_QIAN_WISO

  • QIAN atm input data with water isotopes (CESM I compsets)

  • datm_mode: CLMNCEP

  • streams: CLM_QIAN_WISO.Solar,CLM_QIAN_WISO.Precip,CLM_QIAN_WISO.TPQW

  • datamode: CLMNCEP

DATM%CLM_QIAN

  • QIAN atm input data (CESM I compsets)

  • datm_mode: CLMNCEP

  • streams: CLM_QIAN.Solar,CLM_QIAN.Precip,CLM_QIAN.TPQW

  • datamode: CLMNCEP

DATM%CLMCRUNCEPv7

  • CRUNCEP atm input data (CESM I compsets)

  • datm_mode: CLMNCEP

  • streams: CLMCRUNCEP.Solar,CLMCRUNCEP.Precip,CLMCRUNCEP.TPQW

  • datamode: CLMNCEP

DATM%CLMGSWP3

  • GSWP3 atm input data (I compsets)

  • datm_mode: CLMNCEP

  • streams: CLMGSWP3.Solar,CLMGSWP3.Precip,CLMGSWP3.TPQW

  • datamode: CLMNCEP

DATM%CLM1PT

  • single point tower site atm input data

  • datm_mode: CLMNCEP

  • streams: CLM1PT.$ATM_GRID

  • datamode: CLMNCEP

DATM%ERA5

  • ERA5 atm input data (not used any compset)

  • datm_mode: ERA5

  • streams: ERA5_HOURLY

  • datamode: ERA5

DATM%CPLHIST

  • user generated forcing data from using coupler history files used to spinup relevant prognostic components (for CESM this is CLM, POP and CISM)

  • datm_mode:CPLHIST

  • streams: CPLHISTForcing.Solar,CPLHISTForcing.nonSolarFlux,

  • datamode: CPLHIST

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

DATM_PRESAERO

  • DATM prescribed aerosol forcing mode

DATM_TOPO

  • DATM surface topography forcing (only needed for compsets with active land)

DATM_CO2_TSERIES

  • Full pathname for domain file for datm when DATM_MODE is CPLHIST, NOTE: if this is set to ‘null’ (the default), then domain information is read in from the first coupler history file in the target stream and it is assumed that the first coupler stream file that is pointed to contains the domain information for that stream.

DATM_CPLHIST_CASE

  • Case name used to determine stream filenames when DATM_MODE is CPLHIST

DATM_YR_START

  • Starting year to loop data over

DATM_YR_END

  • Ending year to loop data over

DATM_YR_ALIGN

  • Simulation year corresponding to DATM_YR_START. 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 DATM_YR_START. Another use case is to align the calendar of transient forcing with the model calendar. For example, setting DATM_YR_ALIGN=DATM_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.

DATM_SKIP_RESTART_READ

  • If set to true, than datm restarts will not be read on a continuation run. This capability is used, for example, in CTSM spinup runs.