WRF ARW User's Guide - MMM - UCAR

Real Data Cases
MODEL
For real-data cases, three input options are supported. The first one is similar to running
the idealized cases. That is to have all fields for the nest interpolated from the coarse
domain (input_from_file = T, F). The disadvantage of this option is obvious,
one will not benefit from the higher resolution static fields (such as terrain, landuse, and
so on).
The second option is to set input_from_file = T for each domain, which means
that the nest will have a nest wrfinput file to read in. The limitation of this option is that
this only allows the nest to start at the same time as the coarse domain.
The third option is in addition to setting input_from_file = T for each domain,
also set fine_input_stream = 2 for each domain. Why a value of 2? This is based
on the Registry setting, which designates certain fields to be read in from auxiliary input
stream number 2. This option allows the nest initialization to use 3-D meteorological
fields interpolated from the coarse domain, static fields and masked, time-varying surface
fields from the nest wrfinput. It hence allows a nest to start at a later time than hour 0.
Setting fine_input_stream = 0 is equivalent to the second option.
To run real.exe for a nested run, one must first run WPS and create data for all the
nests. Suppose WPS is run for a 24 hour period, two-domain nest case starting 1200 UTC
Jan 24 2000, and these files should be generated in a WPS directory:
met_em.d01.2000-01-24_12:00:00
met_em.d01.2000-01-24_18:00:00
met_em.d01.2000-01-25_00:00:00
met_em.d01.2000-01-25_06:00:00
met_em.d01.2000-01-25_12:00:00
met_em.d02.2000-01-24_12:00:00
Typically only the first time period of the nest input file is needed to create nest wrfinput
file. Link or move all these files to the run directory.
Edit the namelist.input file and set the correct values for all relevant variables,
described on the previous pages (in particular, set max_dom = 2, for the total number
of domains to run), as well as physics options. Type the following to run:
./real.exe >& real.out
or
mpirun –np 4 ./real.exe
If successful, this will create all input files for coarse as well as nest domains. For a twodomain
example, these are:
wrfinput_d01
wrfinput_d02
wrfbdy_d01
WRF-ARW V3: User’s Guide 5-13