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WRF Tutorial

WRF Tutorial. A Hands-on Overview of the WRF Modeling Process Condensed Version for WFO ANC. July 2009. WRF Architecture. A Typical WRF Run on midnight (Overview). Run a script to install template directories in your filesystem Create a model domain

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WRF Tutorial

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  1. WRF Tutorial A Hands-on Overview of the WRF Modeling Process Condensed Version for WFO ANC July 2009

  2. WRF Architecture

  3. A Typical WRF Run on midnight (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  4. Install Template Directories in Your Filesystem • There is a centralized version of WRF installed on midnight. • However, WRF is set up such that you need to be doing your runs in the same directory as the executables. • We have set up a system that will create template directories in your own filesystem for WPS and WRF • For each domain that you work with, you’ll set up your own WPS/WRF template directories • Example – for a 10km domain over Alaska, you might have your work in directories WPS-Alaska10km and WRFRun-Alaska10km

  5. Run the Setup Script

  6. A Typical WRF Run on midnight (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  7. Create a Model Domain • This step sets up the model domain boundaries, resolution, topography, nests and creates the static file (land use, soil type, etc.) needed by a model run • We only do this once for a given model domain • Procedures • Define your domain – lat/lon, size, resolution, projection, etc. • Edit a namelist file (specifying domain parameters) • Run geogrid.exe to create the domain • Verify successful creation

  8. Namelist file for Domain Creation namelist.wps

  9. Create the Domain netCDF file produced by geogrid.exe

  10. Create the Domain, Then Verify • Run geogrid.exe – this program looks at parameters in namelist.wps, then generates the domain in a netCDF file, geo_em.d01.nc • This file is viewable with various tools, including ncview

  11. Height from geo_em.d01.nc

  12. Or, Generate Map Outline NOTE – you may need to run module load ncl-5.1.0 before idt will work

  13. Nested Domain for Northern US Rockies

  14. Nested Domain for Alaska 9 km 3 km

  15. A Typical WRF Run (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  16. Get Input Data • Numerous sources of different types • Reanalysis for historical runs • Global Final Analysis (FNL) – global coverage, 1-degree resolution • North American Regional Reanalysis (NARR) • Recent model output for real-time runs • North American Mesoscale model (NAM) • Global Forecast System (GFS) • Observations for data assimilation

  17. NAM Grid 216 (AWIPAK)

  18. NAM Grid 212 (AWIP3D)

  19. Observations for Data Assimilation

  20. AVN Input Files for 2005-08-28_00Z

  21. Domain of an AVN Input File

  22. A Typical WRF Run (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  23. Modify namelist.wps

  24. Make Link to Appropriate Vtable

  25. Make links to the input files Contents of /datadir/morton/TutorialData/KatrinaAVN

  26. Run ungrib.exe Ungribbed files

  27. A Typical WRF Run (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  28. Extract and Interpolate Degribbed Data to Match Model Domain • So far, we’ve managed to convert the original input data to an intermediate form • Next, we extract data from the intermediate files that correspond to our selected domain. Where necessary, we interpolate so that the resulting files consist of input values matched to our specific grid • To do all this, we modify namelist.wps (though it’s typically already set up correctly for this), and then we run metgrid.exe

  29. Run metgrid.exe netCDF files containing input data translated and interpolated for our particular grid

  30. A Typical WRF Run (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  31. Extract Initial and Boundary Conditions • The files we created with metgrid.exe represent the input data mapped to our specific domain grid • The next step is to extract what we need from this input data for initial and lateral boundary conditions • To do this, we • Change to our WRFRun directory • Edit namelist.input • Copy the met_em* files produced with metgrid.exe • Run real.exe, and get two files that will contain the boundary conditions for running WRF – wrfbdy_d01 and wrfinput_d01

  32. Get Value of num_metgrid_levels Use ncdump to query one of the met_em* files

  33. namelist.input

  34. namelist.input

  35. Copy the metgrid output to WRFRun directory

  36. Run real.exe (or real-serial.exe) From WPS Lateral BC’s Initial conditions

  37. PSFC from wrfinput_d01(Verify with ncview)

  38. A Typical WRF Run (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  39. Run the Model • Use the same namelist.input from the previous step (real.exe). In most cases you won’t need to modify anything. • Run ./wrf.exe (or ./wrf-serial.exe)

  40. A Typical WRF Run (Overview) • Run a script to install template directories in your filesystem • Create a model domain • Get input data for initial and lateral boundary conditions • Ungrib the input data to an intermediate standard form understood by WRF pre-processing utilities • Extract and interpolate the input data to match the model domain • Extract initial and lateral boundary conditions from input data and modify vertical coordinate system • Run the model • Do something with the output

  41. Postprocessing • The default output file is a netCDF file, named something like wrfout_d01_2005-08-28_00:00:00 • Numerous utilities exist for viewing in native netCDF format, or converting to other formats (e.g. GRIB, Vis5D, BUFR) Start time

  42. ncview Model Output • Using a quick and dirty netCDF viewer to look at model output

  43. Running wrf.exe in Parallel wrfrun.pbs

  44. Submitting PBS Job

  45. Viewing stdout

  46. Viewing stdout

  47. Resources • ARSC-WRF Google Group – http://groups.google.com/group/arsc-wrf • WRF Users Page – http://www.mmm.ucar.edu/wrf/users/ • WRF ARW Users Guide – http://www.mmm.ucar.edu/wrf/users/docs/user_guide_V3/contents.html • WRF ARW Online Tutorial – http://www.mmm.ucar.edu/wrf/OnLineTutorial/index.htm

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