Running WRF

By default, the WRF model is a fully compressible, nonhydrostatic model with a hybrid vertical hydrostatic pressure coordinate (HVC), and Arakawa C-grid staggering. The model uses the Runge-Kutta 2nd and 3rd order time integration schemes, and 2nd to 6th order advection schemes in both the horizontal and vertical. It uses a time-split small step for acoustic and gravity-wave modes. The dynamics conserves scalar variables.

WRF model code contains an initialization program for either real-data (real.exe) or idealized data (ideal.exe), a numerical integration program (wrf.exe), a program allowing one-way nesting for domains run separately (ndown.exe), and a program for tropical storm bogussing (tc.exe). Version 4 of the WRF model supports a variety of capabilities, including

  • Real-data and idealized simulations

  • Various lateral boundary condition options

  • Full physics options, with various filters

  • Positive-definite advection scheme

  • Hydrostatic runtime option

  • Terrain-following vertical coordinate option

  • One-way, two-way, and moving nest options

  • Three-dimensional analysis nudging

  • Observation nudging

  • Regional and global applications

  • Digital filter initialization

  • Vertical refinement for a nested domain


Running Idealized Cases

To run an idealized simulation, the model must have been compiled for the idealized test case of choice, with either a serial compiling option (mandatory for the 1-D and 2-D test cases, or with a parallel computing option (e.g., dmpar, allowed for 3-D test cases). See the following instructions for either a 2-D idealized case, or a 3-D idealized case.

3-D Baroclinic Wave Case

  1. Move to the case running directory.

    cd WRF/test/em_b_wave

  2. Edit the namelist.input file to set integration length, output frequency, domain size, timestep, physics options, and other parameters (see ‘README.namelist’ in the WRF/run directory, or namelist options), and then save the file.

  3. Run the ideal initialization program.

    • For a serial build: ./ideal.exe >& ideal.log

    • For a parallel build: mpirun -np 1 ./ideal.exe

    Note

    ideal.exe must be run with only a single processor (denoted by “-np 1”), even if the code is built for parallel computing.

This program typically reads an input sounding file provided in the case directory, and generates an initial condition file ‘wrfinput_d01.’ Idealized cases do not require a lateral boundary file because boundary conditions are handled in the code via namelist options. If the job is successful, the bottom of the “ideal.log” file (or rsl.out.0000 file for parallel execution) should read SUCCESS COMPLETE IDEAL INIT.

  1. Then to run the WRF model, type

    • For a serial build: ./wrf.exe >& wrf.log

    • For a parallel build: mpirun -np 8 ./wrf.exe * where here we are asking for 8 processors *

Pairs of ‘rsl.out.*’ and ‘rsl.error.*’ files will appear with MPI runs. These are standard out and error files. There will be one pair for each processor used. If the simulation was successful, the wrf output is written to a file named “wrfout_d01_0001-01-01_00:00:00,” and the end of the “wrf.log” file (or rsl.out.0000) should read wrf: SUCCESS COMPLETE WRF.

Output files ‘wrfout_d01_0001-01-01*’ and restart files ‘wrfrst*’ should be present in the run directory, depending on how namelist variables are specified for output. The time stamp on these files originates from the start times in the namelist file.