Python scripts for downloading ERA-Interim 0.75 degree from ECMWF data server (batch access). All necessary input fields for WRF are used.
The journal article describing the ERA-Interim reanalysis is available from the Quarterly Journal of the Royal Meteorological Society at: http://onlinelibrary.wiley.com/doi/10.1002/qj.828/abstract. See also DATA FAQ.
Python scripts download daily fields (full resolution) on pressure levels ('pl') and at the surface ('sfc') in one file for every month and take leap years into account.
Note for the first time use:
In addition to that, one needs 2 time invariant fields:
var172 - lsm - Land-sea mask var129 - z - Geopotential
Ungrib both separatly (as you would ungrib all other data files: set prefix in &ungrib, link_grib.csh, ungrib.exe) and add them as constant fields to the namelist.wps, &metgrid section:
constants_name = '/path/to/invariant/data/LSM:1989-01-01_12', '/path/to/invariant/data/Z:1989-01-01_12'