WRF preprocessing

17.4.4.3. WRF preprocessing#

WRF pre-processing system is WPS.

Warning

It should be downloaded in the same version than WRF.

Instructions, and scripts are provided in ~/croco/croco_tools/Coupling_tools/WRF_WPS. You can follow the instructions given in readme_wps, and use the provided scripts: run_wps.bash, job.wps.*

Note: you will need to have WPS compiled before (see preivous compilation tuto).

17.4.4.3.1. Running WPS#

WRF pre-preocessing with WPS contains 3 steps:

  • geogrid: defining the horizontal domain and interpolating geographical static data

  • ungrib: decoding Grib meteorological data from reananlyses (or so)

  • metgrid: interpolating meteorological data on the model grid

To run WPS, you therefore need:

  • Geographical data Geographical data for WRF are available on WRF users website http://www2.mmm.ucar.edu/wrf/users/download/get_source.html. Geographical data will be available following the link ”here” under WPS download section. You can download the full complete set, but note that topo files are not all in it. Download them individually in addition (e.g. topo_30s). Note that Geographical data file is a VERY LARGE file (49 Go uncompressed). Uncompress them (tar xvjf or tar -zxvf).

  • Reanalysis data in grib format (from CFSR for example) to build the boundary and initial conditions. For example, CFSR data can be downloaded from: https://rda.ucar.edu/datasets/ds093.0/index.html#!description A dedicated readme for CFSR data download is provided in croco_tools/Coupling_tools/WRF_WPS. You can use g1print.exe or g2print.exe (depending on you grib data format) available in WPS/ungrib/ to check the variables in your data files. Usage is

    ./g2print.exe YOURDATAFILE

  • Vtable to read the grib data: exsiting Vtables can be found in WPS source directory under WPS/ungrib/Variable_Tables, and informations to choose Vtables can be found here: http://www2.mmm.ucar.edu/wrf/users/download/free_data.html

    Note

    For CFSR, you will need 2 Vtables: one for the fields on pressure levels, one for the fields on surface level. Both Vtables are available in croco_tools/Coupling_tools/WRF_WPS directory

    Vtable.CFSR_press_pgbh06
Vtable.CFSR_sfc_flxf06

    ungrib therefore needs to be run twice (once for each type). This is done in run_wps.bash (see below).

A few scripts have been made to help you run WPS. You can find them in your croco_tools/Coupling_tools/WRF_WPS directory:

  • configure.namelist.wps

  • run_wps.bash

  • job.wps.*

  1. You should find them in YOURCONFIG/PREPRO/WRF_WPS. Edit all the required lines in configure.namelist.wps, and edit all the required paths in run_wps.bash

  2. Run WPS directly (or using job.wps.pbs if you need to submit it in batch)

    ./run_wps.bash configure.namelist.wps NBPROCS >& run_wps.log

    If WPS is successful, you will obtain in ~/CONFIGS/BENGUELA_cpl/WRF_FILES/WPS_DATA

    geo_em.d01.nc
geo_em.d02.nc
met_em.d01.....nc # numerous files where ’...’ are dates
met_em.d02.....nc # numerous files where ’...’ are dates

  3. Check your metgrid files by looking at some variables with ncview (e.g. LANDMASK, PSFC, PSML, SKINTEMP, TT …)

    If some variables are missing, it is probably because you did not process ungrib and metgrid for all your input data.

    If something appears weird, it may be due to a bad interpolation (for example due to a too coarse land-sea mask in the original data). If so, re-run WPS with an updated METGRID.TBL

17.4.4.3.2. Running real.exe#

After running WPS pre-processing, you need to run real.exe program which actually creates WRF input files for realistic cases from WPS generated files.

Warning

You need to use real.exe from uncoupled compilation even for a coupled run

A script has been made to help you run real.exe: run_real.bash. You can find it in your ~/CONFIGS/BENGUELA_cpl/WRF_IN directory or in the croco/SCRIPTS/SCRIPTS_COUPLING/WRF_IN. It also uses:

  • configure.namelist.real

  • namelist.input.base.complete

  1. Edit all the required lines in configure.namelist.real, and edit all the required paths in run_real.bash

  2. Eventually edit namelist.input.base.complete with you choice of parameterization. DO NOT EDIT the stuff placed into brackets: <...>, it will be replaced by run_real.bash with appropriate values.

    Warning

    For coupling with waves and currents, only YSU surface and boundary layer schemes are possible at the moment. Be sure to select these.

  3. Run run_real.bash (eventually using a batch job as job.real.pbs):

    ./run_real.bash configure.namelist.real NBPROCS >& run_real.log

    If real is successful, you will obtain in ~/CONFIGS/BENGUELA_cpl/WRF_FILES/YYYY

    wrfinput_d01_DATE
wrfbdy_d01_DATE
wrflowinp_d01_DATE # if sst_update is set to 1
wrfdda_d01_DATE # if nudging is activated i
wrf*_d02_DATE # if you have 2 domains

17.4.4.3.3. Additional pre-processing for coupled runs#

In addition to traditional WRF pre-processing, you will need to:

  • edit options in namelist.input:

    • in &physics: isftcflx = 5 if your are coupling with a wave model

    • in &physics: sst_update = 1 if your are coupling with an ocean model

    • in &domains: num_ext_model_couple_dom = X : number of domains of the other model you are coupling to WRF

      • edit CPLMASK variable in wrfinput_d0X for all your coupled domains:

        • CPLMASK=1 where you want to couple

        • CPLMASK=0 when you do no want to couple

    • you may need to create a WRF grid file for OASIS, if you are using the distributed version of WRF (at the date of 2021-Nov). If you are using the github WRF-CROCO version, you don’t need to create this grid file, it will be created automatically. If necessary, a script is provided in croco/SCRIPTS/SCRIPTS_COUPLING/SCRIPTS_TOOLBOX/OASIS_SCRIPTS:

      Edit and run create_oasis_grids_for_wrf.sh

Note that the CPLMASK creation may also be performed automatically in the coupling tools.

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