WRF Pre-Processing System Version 4.6.0
http://www2.mmm.ucar.edu/wrf/users/
The WRF Pre-Processing System (WPS) is a collection of Fortran and C programs that provides data used as input to the real.exe program. There are three main programs and a number of auxiliary programs that are part of WPS.
For questions and help to run the program, please see the User's Guide at http://www2.mmm.ucar.edu/wrf/users/docs/user_guide_v4/contents.html and send email to wrfhelp@ucar.edu.
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Main programs: geogrid.exe, ungrib.exe, metgrid.exe
Input to the main programs is through the namelist file "namelist.wps". Each main program has an exclusive namelist record (named "geogrid", "ungrib", or "metgrid", respectively), and the three programs have a group record (named "share") that each program reads.
1) Defines the model horizontal domain 2) Horizontally interpolates static data to the model domain 3) Output conforms to the WRF I/O API
1) Decodes Grib Edition 1 and 2 data 2) Uses tables to decide which variables to extract 3) Supports isobaric and generalized vertical coordinates 4) Output is in a non-WRF-I/O-API form, referred to as an intermediate format
1) Ingest static data and raw meteorological fields 2) Horizontally interpolate meteorological fields to the model domain 3) Output conforms to WRF I/O API
Parallelism
The geogrid and metgrid programs may be run as distributed memory parallel jobs to reduce the time-to-solution. These two programs use MPI calls directly, compared to WRF, which has an abstraction layer (RSL or RSL_LITE).
Grib Edition 2
The Grib Edition 2 compression requires three libraries external to the WPS source code: zlib, png, and jasper. It is recommended that users request support from their system administrators when installing these packages. Users can compile the code without these libraries by selecting the "NO GRIB2" options in the build.
Building WPS
Similar to the WRF package, WPS uses a two-step build mechanism, ./configure ./compile which directs the unix make underneath. If the user is on a recognized architecture, the configure script will display a list of available compile options (usually serial vs parallel, Grib 2 enabled vs a "NO GRIB2" option). For some OS options, there are multiple compilers that are supported.
The configure option lists both "build GRIB2" and "do not build GRIB2" options. It is suggested that the first builds be without the GRIB Edition 2 capability.
The utility plotting programs requiring NCAR Graphics are not compiled automatically. Library paths must be set correctly in configure.wps and then compiled using ./compile plotfmt ./compile plotgrids
Building WPS with CMake
The WPS cmake build follows the same procedure as the WRF build procedure, using the following: ./configure_new ./compile_new
The prompts will look similar and present the user with available options specific to their system.
Running WPS (for serially compiled code)
There are a number of utility programs that will be built in WPS/util/ directory:
purpose: computes a daily mean of the surface air temperature, reads the namelist.wps file
usage: avg_tsfc.exe
purpose: read a Grib Edition 1 file, output information to build a Vtable
usage: g1print.exe GRIB1_file
purpose: read a Grib Edition 2 file, output information to build a Vtable
usage: g2print.exe GRIB2_file
purpose: reduce levels in a intermediate file so that different GRIB sources may be used for the initial and lateral boundary time periods
usage: mod_levs.exe OLD_intermetdiate:date_string \ NEW_intermetdiate:date_string Processes a single file at a time, uses the pressure levels defined in the namelist.wps file.
purpose: generate NCAR Graphics metacode 2d horizontal plots of each field and level in the intermediate file
usage: plotfmt.exe intermediate_file:date_string
purpose: generate an NCEAR Graphics metacode plot of the domain locations, one frame with all of the domain locations plotted, reads the namelist.wps file to get the domain information
usage: plotgrids.exe
purpose: read an intermediate file and print the information to the screen
usage: rd_intermediate.exe intermediate_file:date_string
purpose: when using ECMWF model data in GRIB format, computes the 3-d pressure, height, and RH fields from the output of ungrib.exe, and writes these fields to a new set of intermediate files to be used in addition to those produced by ungrib. All times between the start_date and end_date specified in the &share namelist will be processed.
usage: calc_ecmwf_p.exe
Static Input Data
The static input data is provided in two tar files: one contains full resolution data (30", 2', 5' and 10') and the other contains only 10' low-resolution data. The data may be downloaded from http://www2.mmm.ucar.edu/wrf/users/download/get_source.html.
Meteorological Input Data
The meteorological input data for WPS is the GRIB Edition 1 GFS data from NCEP. A test data set (Jan 2000, 24/12Z to 25/12Z) is available from http://www2.mmm.ucar.edu/wrf/users/download/get_source.html.
Sample WPS output data for WRF
Samples of the output data from WPS for use in WRF for the Jan 2000 and June 2001 cases are provided from http://www2.mmm.ucar.edu/wrf/users/download/get_source.html.