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WRF Tutorial

WRF Tutorial. For Version 3.0.1.1 / Synoptic Lab January, 2009 Robert Fovell rfovell@ucla.edu. http://www.atmos.ucla.edu/~fovell/WRF/wrf_tutorial_2009.ppt.htm. Background on WRF model. “Weather Research and Forecasting” Co-developed by research and operational communities

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WRF Tutorial

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  1. WRF Tutorial For Version 3.0.1.1 / Synoptic Lab January, 2009 Robert Fovell rfovell@ucla.edu http://www.atmos.ucla.edu/~fovell/WRF/wrf_tutorial_2009.ppt.htm

  2. Background on WRF model • “Weather Research and Forecasting” • Co-developed by research and operational communities • ARW core “Advanced Research WRF” • NMM core “Nonhydrostatic Mesoscale Model” • Supercedes MM5 and Eta models • Current version 3.0.1.1 • Platforms include Linux and Mac OS X

  3. WRF advantages • Better numerics than MM5 • Arakawa C grid, R-K scheme, odd order advection w/ implicit diffusion • Much less diffusive, larger effective resolution, permits longer time steps • Better handling of topography than Eta (original NAM) • NAM model is now WRF-NMM • Fortran 95 and C (MM5 was F77) • NetCDF, GRIB1 and GRIB2

  4. Further advantages • MPI from the ground up • Allows real data and idealized simulations in same framework • Plug-in architecture (different groups will supply WRF “cores”) • Recently added: moving nests and nudging • NetCDF output - many great tools such as NetCDF operators: http://nco.sourceforge.net/ • GRIB2 output now possible as well

  5. WRF disadvantages • Bleeding edge • Smaller range of physics choices (changing quickly…) • Software design is unintuitive for physical scientists • Can take hours to compile • But does not need frequent recompiling • Comparatively slower than MM5 • NetCDF files can be huge

  6. WRF and related software • WRF Preprocessing System (WPS) • Replaces/supercedes WRF SI • WRF-ARW model • Single node, OpenMP and MPI • WRF postprocessing software • RIP (read/interpolate/plot) • GrADS • NCL • Specific to “hurricane” Synoptic Lab environment • Neglecting for now: ARWpost, WRF Chem, WRF Var, MET (Verification software), VAPOR, Vis5D

  7. Web resources • WRF model users site http://www.mmm.ucar.edu/wrf/users • ARW users’ guide http://www.mmm.ucar.edu/wrf/users/docs/user_guide/contents.html • WRF-ARW/WPS online tutorial http://www.mmm.ucar.edu/wrf/users/docs/user_guide_V3/contents.html • WRF namelist description http://www.mmm.ucar.edu/wrf/users/docs/user_guide_V3/users_guide_chap5.htm#_Description_of_Namelist • Tutorial presentations http://www.mmm.ucar.edu/wrf/users/supports/tutorial.html

  8. My resources • This presentation (PPT format) http://www.atmos.ucla.edu/~fovell/WRF/wrf_tutorial_2009.ppt • WRF on Mac OS X http://macwrf.blogspot.com

  9. Setup on “hurricane” machines Presumed: • tcsh environment • Intel Fortran compiler (64-bit) • my environment setup employed • precompiled versions of WRF, WPS, RIP and wrf_to_grads

  10. Environment setup>…is the command line prompt • If you don’t have a .cshrc file (worth saving) - recommended > cp /home/fovell/.cshrc . > source .cshrc • If you want to keep your present .cshrc > cp /home/fovell/cshrc_fovell.csh . > ./cshrc_fovell.csh [you would need to do this every time, in every window]

  11. # RGF additions [abridged] setenv RIP_ROOT /home/fovell/RIP4 setenv GADDIR /home/fovell/lib/grads setenv GASCRP /home/fovell/gradslib # alias lsm 'ls -alt | more' alias rm 'rm -i' alias cp 'cp -i' alias mv 'mv -i' alias trsl ' tail -f rsl.out.0000' alias mpirun 'nohup time /home/fovell/mpich-1.2.7p1/bin/mpirun' alias w2g '/home/fovell/WRF2GrADS/wrf_to_grads' setenv P4_GLOBMEMSIZE 4096000 setenv P4_SOCKBUFSIZE 65536 unlimit limit coredumpsize 0 This environment uses my versions of netcdf, mpich, grads, RIP

  12. Set up a run directory > cd > mkdir SQUALL > cd SQUALL > cp /home/fovell/WRFtutorial/make_all_links.csh . > make_all_links.csh > cp /home/fovell/WRFtutorial/namelist.* . [copies namelist.input, namelist.wps]

  13. WRF for real-data run A 2006 squall-line [This example uses data that may not remain online]

  14. Surface map 00Z April 3, 2006

  15. Radar 00Z April 3, 2006

  16. WPS overview • Tasks • (1) set up a domain (can be reused) • geogrid.exe • (2) unpack parent model data (e.g., from GFS, NAM, etc.) • ungrib.exe • (3) prepare unpacked data for WRF • metgrid.exe • Controlled by namelist.wps • Input data source: FNL analysis

  17. namelist.wps &share wrf_core = 'ARW', max_dom = 3, start_date = '2006-04-02_18:00:00', '2006-04-02_18:00:00','2006-04-02_18:00:00', end_date = '2006-04-04_00:00:00', '2006-04-04_00:00:00','2006-04-04_00:00:00', interval_seconds = 21600 io_form_geogrid = 2, / • Setup for 3 telescoping domains • For start_date, end_date need one column for each domain • interval_seconds is parent model data frequency (here, 6 h f • or FNL data)

  18. namelist.wps (cont.) &geogrid parent_id = 1, 1, 2, parent_grid_ratio = 1, 3, 3, i_parent_start = 1, 15, 30, j_parent_start = 1, 15, 37, e_we = 70, 133, 190, e_sn = 70, 133, 190, geog_data_res = '10m','2m','30s', dx = 36000, dy = 36000, map_proj = 'lambert', ref_lat = 39., ref_lon = -88.00, truelat1 = 30.0, truelat2 = 60.0, stand_lon = -88.00, geog_data_path = '/home/fovell/WPS_GEOG/geog' / there is more…

  19. geogrid - create domain > geogrid.exe * creates geo_em.d0*.nc (a NetCDF file) * look for “Successful completion of geogrid.” > plotgrids.exe * creates gmeta > idt gmeta * uses NCAR graphics tool to view domain

  20. > ncdump geo_em.d01.nc | more netcdf geo_em.d01 { • dimensions: • Time = UNLIMITED ; // (1 currently) • DateStrLen = 19 ; • west_east = 69 ; • south_north = 69 ; • south_north_stag = 70 ; • west_east_stag = 70 ; • land_cat = 24 ; • soil_cat = 16 ; • month = 12 ; • variables: • char Times(Time, DateStrLen) ; • float XLAT_M(Time, south_north, west_east) ; • XLAT_M:FieldType = 104 ; • XLAT_M:MemoryOrder = "XY " ; • XLAT_M:units = "degrees latitude" ; • XLAT_M:description = "Latitude on mass grid" ; • XLAT_M:stagger = "M" ;

  21. Parent model data issues • Sources include GFS, FNL, NAM, RUC, NARR and NNRP reanalysis data, etc. • Need a different Vtable (variable table) for each source • e.g., Vtable.GFS, Vtable.NAM, Vtable.NARR, etc. • Look in /home/fovell/WRFtutorial

  22. Accessing parent model data > link_grib.csh /home/fovell/FNL2006/fnl * links to where parent model for case resides ** data files start with ‘fnl*’ > ln -sf /home/fovell/WRFtutorial/Vtable.GFS Vtable * specifies appropriate Vtable > ungrib.exe * extracts parent model data * look for “Successful completion of ungrib.”

  23. Next step: metgrid > metgrid.exe ...hopefully you see ... “Successful completion of metgrid.” ...Output looks like... met_em.d01.2006-04-02_18:00:00.nc met_em.d02.2006-04-03_12:00:00.nc met_em.d01.2006-04-03_00:00:00.nc met_em.d02.2006-04-03_18:00:00.nc met_em.d01.2006-04-03_06:00:00.nc met_em.d02.2006-04-04_00:00:00.nc met_em.d01.2006-04-03_12:00:00.nc met_em.d03.2006-04-02_18:00:00.nc met_em.d01.2006-04-03_18:00:00.nc met_em.d03.2006-04-03_00:00:00.nc met_em.d01.2006-04-04_00:00:00.nc met_em.d03.2006-04-03_06:00:00.nc met_em.d02.2006-04-02_18:00:00.nc met_em.d03.2006-04-03_12:00:00.nc met_em.d02.2006-04-03_00:00:00.nc met_em.d03.2006-04-03_18:00:00.nc met_em.d02.2006-04-03_06:00:00.nc met_em.d03.2006-04-04_00:00:00.nc

  24. ncdump on a metgrid file netcdf met_em.d01.2006-04-02_18:00:00 { dimensions: Time = UNLIMITED ; // (1 currently) DateStrLen = 19 ; west_east = 69 ; south_north = 69 ; num_metgrid_levels = 27 ; This data source has 27 vertical levels. This will vary with source - so check an met_em* file.

  25. WRF model steps • Tasks • Run real.exe (to finish creation of WRF model input data) • Run wrf.exe • Both use namelist.input • Configured separately from namelist.wps but includes overlapping information • Examples set up to use OpenMP on a single node (i.e., WRF will use 1 or more cores)

  26. namelist.input &time_control run_days = 0, run_hours = 12, run_minutes = 0, run_seconds = 0, start_year = 2006, 2006, 2006, start_month = 04, 04, 04, start_day = 02, 02, 02, start_hour = 18, 18, 18, start_minute = 00, 00, 00, start_second = 00, 00, 00, end_year = 2006, 2006, 2006, end_month = 04, 04, 04, end_day = 03, 03, 03, end_hour = 06, 06, 06, end_minute = 00, 00, 00, end_second = 00, 00, 00, For start_*, end_*, one column per domain

  27. namelist.input (cont.) interval_seconds = 21600 input_from_file = .true.,.true.,.true., history_interval = 60, 60, 60, frames_per_outfile = 1, 1, 1, restart = .false., restart_interval = 5000, interval_seconds matches namelist.wps input_from_file should normally be ‘true’ for each domain history_interval - how frequently (in min) output created frames_per_outfile - number of writes in each history file If wish to restart mode, restart = .true. (and set model start_* data to restart time) restart_interval = frequency (min) for writing restart files

  28. namelist.input (cont.) &domains time_step = 60, time_step_fract_num = 0, time_step_fract_den = 1, max_dom = 1, s_we = 1, 1, 1, e_we = 70, 133, 190, s_sn = 1, 1, 1, e_sn = 70, 133, 190, s_vert = 1, 1, 1, e_vert = 51, 51, 51, num_metgrid_levels = 27 dx = 36000, 12000, 4000, dy = 36000, 12000, 4000, grid_id = 1, 2, 3, parent_id = 0, 1, 2, i_parent_start = 0, 15, 30, j_parent_start = 0, 15, 37, parent_grid_ratio = 1, 3, 3, parent_time_step_ratio = 1, 3, 3,

  29. namelist.input (cont.) &physics mp_physics = 3, 3, 3, ra_lw_physics = 1, 1, 1, ra_sw_physics = 1, 1, 1, radt = 10, 10, 10, cam_abs_freq_s = 21600, cam_abs_dim1 = 4, cam_abs_dim2 = 51, levsiz = 59, paerlev = 29, sf_sfclay_physics = 1, 1, 1, sf_surface_physics = 2, 2, 2, bl_pbl_physics = 1, 1, 1, bldt = 0, 0, 0, cu_physics = 1, 1, 0, cudt = 5, 5, 5, there is more…

  30. Notes on physics • Need to use SAME microphysics (mp) scheme in each domain, but can use different cumulus (cu) schemes • Some physics combinations work better than others, some don’t work at all -- this is only lightly documented • bldt = 0 means boundary layer (bl) scheme is called every time step • Standard practice: call bl every time step, cu every 5 min, ra (radiation) every 10 min

  31. namelist.input (cont.) &dynamics w_damping = 0, diff_opt [subgrid turbulence] = 1, km_opt [ “ ] = 4, diff_6th_opt [numerical smoothing] = 0, diff_6th_factor [ “ ] = 0.12, base_temp = 290. damp_opt = 0, zdamp = 5000., 5000., 5000., dampcoef = 0.01, 0.01, 0.01 khdif = 0, 0, 0, kvdif = 0, 0, 0, Only some diff_opt/km_opt combinations make sense, and choices are resolution-dependent. More info: http://www.mmm.ucar.edu/wrf/users/supports/tutorial.html

  32. http://www.mmm.ucar.edu/wrf/users/tutorial/200901/WRF_Physics_Dudhia.pdfhttp://www.mmm.ucar.edu/wrf/users/tutorial/200901/WRF_Physics_Dudhia.pdf

  33. real.exe • Has changed a lot since version 2.1.2 • Number of vertical model levels is specified in this step • The num_metgrid_levels comes from parent model; you set e_vert (number of WRF levels) here • Can reset WRF levels by rerunning real.exe • Can also specify which levels you want e_vert = 51, 51, 51, num_metgrid_levels = 27

  34. Setting levels in namelist.input(optional) • WRF uses “sigma” or “eta” coordinates (1.0 is model • bottom, 0.0 is top) • Added lines to &domains in namelist.input, presuming • e_vert = 51, requests a model top pressure of 50 mb • (5000 Pa) and concentrates vertical resolution in lower trop p_top_requested = 5000 eta_levels = 1.00,0.9969,0.9935,0.9899,0.9861,0.9821, 0.9777,0.9731,0.9682,0.9629,0.9573,0.9513, 0.9450,0.9382,0.9312,0.9240,0.9165,0.9088, 0.9008,0.8925,0.8840,0.8752,0.8661,0.8567, 0.8471,0.8371,0.8261,0.8141,0.8008,0.7863,0.7704, 0.7531,0.7341,0.7135,0.6911,0.6668,0.6406, 0.6123,0.5806,0.5452,0.5060,0.4630,0.4161, 0.3656,0.3119,0.2558,0.1982,0.1339,0.0804,0.0362,0.0000,

  35. Run real.exe and wrf.exe > setenv | grep OMP OMP_NUM_THREADS=4 > real.exe [look for…] d01 2006-04-03_06:00:00 real_em: SUCCESS COMPLETE REAL_EM INIT • max_dom in namelist.input is set to 1… although we created three domains, only one will be used in the run

  36. Run wrf.exe • Output of real.exe is wrfbdy_d01 and wrfinput_d01 (NetCDF files) - Input files created for each domain, up to max_dom • Run the model > nohup time wrf.exe > wrf.out & • Creates wrfout_d0* files keyed by simulation date for each domain > tail -f wrf.out [to watch the model run]

  37. WRF model output • Namelist set up to do 12 h run • Look for at end of wrf.out file: d01 2006-04-03_06:00:00 wrf: SUCCESS COMPLETE WRF • Output files created: • This is because history_interval was 60 min and frames_per_outfile was 1 wrfout_d01_2006-04-02_18:00:00 wrfout_d01_2006-04-03_01:00:00 wrfout_d01_2006-04-02_19:00:00 wrfout_d01_2006-04-03_02:00:00 wrfout_d01_2006-04-02_20:00:00 wrfout_d01_2006-04-03_03:00:00 wrfout_d01_2006-04-02_21:00:00 wrfout_d01_2006-04-03_04:00:00 wrfout_d01_2006-04-02_22:00:00 wrfout_d01_2006-04-03_05:00:00 wrfout_d01_2006-04-02_23:00:00 wrfout_d01_2006-04-03_06:00:00 wrfout_d01_2006-04-03_00:00:00

  38. Postprocessing WRF output:RIP and GrADS(Vis5D, ARWpost and VAPOR also exist)

  39. RIP • RIP operates in batch mode, using input scripts • RIP can overlay fields, do arbitrary cross-sections, calculate trajectories, and create Vis5D output files • RIP tasks include • Unpack model output data (ripdp_wrf) • Create RIP plotting scripts (rip.in files) • Execute scripts (rip) • RIP can create a LOT of output files

  40. RIP procedure > cp /home/fovell/WRFtutorial/rip.T2.in . > ripdp_wrf run1 all wrfout_d01* [this creates a new dataset called ‘run1’ and uses all wrfout_d01 files created] > rip run1 rip.T2.in [the rip.T2.in file is a script containing RIP plotting commands] [the output file, rip.T2.cgm, is a graphics metafile] You can view the cgm file using idt or ictrans

  41. Domain 1 terrain

  42. 12 h forecast(2m T - color; 1h precip totals; 10 m vector winds)

  43. 12 h forecast(2m T - color; 1h precip totals; 10 m vector winds)

  44. RIP script =========================================================================== feld=T2; ptyp=hc; vcor=s; levs=1fb; cint=1; cmth=fill;> arng; cbeg=273; cend=303; cosq=0,violet,12.5,blue,25,green,37.5,> light.green,50,white,62.5,yellow,75,orange,87.5,red,100,brown feld=U10,V10; ptyp=hv; vcmx=20.0; colr=black; linw=1; intv=2; feld=slp; ptyp=hc; vcor=s; levs=1fb; cint=4; nohl;colr=blue;linw=2;nolb feld=map; ptyp=hb; colr=dark.blue; linw=2; feld=tic; ptyp=hb =========================================================================== http://www.mmm.ucar.edu/wrf/users/docs/ripug.htm

  45. GrADS and wrf_to_grads • GrADS produces beautiful graphics • Batch scriptable AND interactive • Interactive: good for overlaying different datasets, computing difference fields [can also be done in RIP] • Doesn’t create huge numbers of intermediate files like RIP • Arbitrary cross-sections are difficult to construct

  46. GrADS procedure • Copy control_file from /home/fovell/WRFtutorial and edit • Select variables desired and define wrfout files to be accessed (next slide) • w2g control_file run1g • Creates run1g.ctl, run1g.dat http://grads.iges.org/grads/head.html

  47. control_file -3 ! times to put in GrADS file, negative ignores this 0001-01-01_00:00:00 0001-01-01_00:05:00 0001-01-01_00:10:00 end_of_time_list ! 3D variable list for GrADS file ! indent one space to skip U ! U Compoment of wind V ! V Component of wind UMET ! U Compoment of wind - rotated (diagnostic) VMET ! V Component of wind - rotated (diagnostic) W ! W Component of wind THETA ! Theta TK ! Temperature in K TC ! Temperature in C List of available 2D fields follows

  48. control_file (cont.) ! All list of files to read here ! Indent not to read ! Full path OK wrfout_d01_2006-04-02_18:00:00 wrfout_d01_2006-04-02_19:00:00 wrfout_d01_2006-04-02_20:00:00 [more…] end_of_file_list ! Now we check to see what to do with the data real ! real (input/output) / ideal / static 1 ! 0=no map background in grads, 1=map background in grads -1 ! specify grads vertical grid ! 0=cartesian, ! -1=interp to z from lowest h ! 1 list levels (either height in km, or pressure in mb) 1000.0 950.0 900.0 850.0 800.0 750.0 [more…]

  49. Running GrADS > gradsnc -l [GrADS graphics output window opens] ga-> open run1g [ga-> is GrADS environment prompt] ga-> /home/fovell/WRFtutorial/T2_movie.gs [executes this GrADS script; hit return to advance a frame] ga-> quit [to exit]

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