How to run WRF with ERA-Interim data

How to run WRF with ERA-Interim data#

Running WRF from ERA-Interim#

The CMS team helps to maintain a mirror of the ERA-Interim reanalysis data set at NCI, which can be used as the boundary conditions for a WRF run. The GRIB files may be found under /g/data/ub4/erai/grib/, you will need to request access to the dataset first in order to access it.

You can use Vtable.ERA-interim.pl to ungrib the ERA-Interim data, using the grib files under directories oper_an_pl. This Vtable file can be found in the WPS distribution under ungrib/Variable_Tables. You will also need to ungrib the files in directory oper_an_sfc to get the surface fields.

Automatic WPS#

We have a script available at wps-era on Github that will run all WPS steps automatically for you using the pressure level dataset. You can download the script with git:

git clone https://github.com/coecms/wps-era
cd wps-era

Edit the namelist.wps file as appropriate for your model, then run WPS with

make WPSDIR=/path/to/WPS

WPSDIR should be the path where you compiled WPS. The script will read the run dates from the namelist, and link in only the files required for the period you’re using.

Manual WPS#

Time dependent data#

To run ungrib on both the surface and vertical data you can either create a temporary directory with both types of files, and run link_grib.csh on that directory:

mkdir era-tmp
ln -s /g/data/ub4/erai/grib/oper_an_pl/fullres/2006/ei_oper_an_pl_075x075_90N0E90S35925E_200603* era-tmp
ln -s /g/data/ub4/erai/grib/oper_an_sfc/fullres/ei_oper_an_sfc_075x075_90N0E90S35925E_200603* era-tmp
./link_grib.csh era-tmp/*
./ungrib.exe

OR you can use different ungrib prefixes for the surface and vertical fields, combining the files with metgrid:

./link_grib.csh /g/data/ub4/erai/grib/oper_an_pl/fullres/2006/ei_oper_an_pl_075x075_90N0E90S35925E_200603*
nano namelist.wps # Set ungrib/prefix to 'PL'
./ungrib.exe

./link_grib.csh /g/data/ub4/erai/grib/oper_an_sfc/fullres/ei_oper_an_sfc_075x075_90N0E90S35925E_200603*
nano namelist.wps # Set ungrib/prefix to 'SFC'
./ungrib.exe

Invariant Data#

You will also need to generate the invariant data, which includes the land-sea mask used for interpolating the ERA Interim source dataset to your model’s target resolution The invariant data is only defined at 19890101T1200Z, so you need to set the start and end dates in namelist.wps to this value (if you’re using multiple nests set all of the dates)

&share
    ! Keep other settings the same, change dates to
    start_date = '1989-01-01_12:00:00',
    end_date = '1989-01-01_12:00:00',
/
&ungrib
     out_format = 'WPS'
     prefix = 'INV'
/

./link_grib.csh /g/data/ub4/erai/grib/invariant/ei_oper_an_sfc_075x075_90N0E90S3585E_invariant
./ungrib.exe

Remaining processing#

Before running Metgrid you need to tell it about all of the input GRIB datasets. In namelist.wps set fg_name to a list of the time dependent datasets, and set constants_name to INV:1989-01-01_12

&metgrid
 fg_name = 'SFC', 'PL'
 io_form_metgrid = 2,
 constants_name = 'INV:1989-01-01_12'
/

You can then run geogrid and metgrid as normal to generate the input files (don’t forget to change back the run dates if you changed them for the invariant ungrib).