WRF Post-Processing

1. WRF Post-Processing Wei Wang NCAR/MMM

2. Outline • NetCDF data • NCL • General information • How is it used in WRF post-processing? • How to run it? • WRF-to-Vis5D • RIP

3. netCDF Data

4. netCDF Data • netCDF is one of the data formats chosen for WRF I/O, and is currently supported. • What is netCDF? netCDF stands for Network Common Data Form netCDF is “an interface to a library of data access functions for storing and retrieving data in the form of arrays.” (http://www.unidata.ucar.edu/) • Documentation available at above site.

5. netCDF Data (cont) • What are the advantages of using netCDF? • Platform-independent (no big_endian, little_endian) – though it may be with some caveat.. • Many software may already exist which can be used to process netCDF data.

6. netCDF Data (cont) • netCDF utilities available: • ncdump reads a netCDF dataset and prints a textual representation of the information in the dataset e.g. ncdump –h file -- print header (inc. variables in the file) ncdump –v variable-name file-- print values of the var • ncgen generates a netCDF file or a C or FORTRAN program that creates a netCDF dataset

7. netCDF Data (cont) • Other netCDF operators are available from http://nco.sourceforge.net/, which can be used to manipulate data, such as performing grid point averaging, file differencing, and file ‘appending’.

8. netCDF Data (cont) • In WRF system, simple utilities are also available. See for example, module_wrf_to_v5d_util.F in wrf2vis5d.tar file.

9. netCDF Data (cont) • Simple calls to access the data. For example, call get_dims_cdf( file_for_time(1), 'T', & dims, ndims, debug ) > get dimensions of field T in an array dims call get_gl_att_real_cdf( file_for_time(1), & 'CEN_LON', cen_lon, debug ) > get attributes from a netCDF file call get_var_2d_real_cdf( file_for_time(1), & 'XLAT', xlat, dims(1), dims(2), 1, debug) > get the 2D field XLAT (similar call for a 3D field)

10. NCL in WRF Slides contributions from Bill Skamarock and Ethan Alpert (NCAR/SCD)

11. What is NCL? • NCL stands for NCAR Command Language • NCL is an interpreted programming language • Array based algebraic operators • Support netCDF data • Wide variety of graphics capabilities: • Maps, Contours, XY, Vectors, Streamlines, labelbars, text, tickmarks as well as line, marker and polygon primatives • Output to X, NCGM, PostScript

12. What is NCL? • NCL is available on most UNIX platforms • NCL can run in batch or interactive mode • Interactive mode has command history and command line editing • Many useful functions and procedures • Code integration tool (ability to import FORTRAN) • Pre-compiled binaries are free.

13. Downloading NCL • Go to: • http://ngwww.ucar.edu/ncl/download • Read and agree to GPL license • Fill out short registration form • Download binaries • Precompiled versions exist for: • IBM RS6000, DEC Alpha, Sun Solaris, RedHat Linux, SGI IRIX, Alpha running RedHat Linux, and Mac running OSX

14. Important resources forusing and learning NCL • NCL home page: • http://ngwww.ucar.edu/ncl • Contains links to documentation, examples, FAQ, ncl-talk email list, and update information

15. Getting Started Using NCL (GSUN) • Getting Started Using NCL (GSUN) • http://ngwww.ucar.edu/ngdoc/ng/ug/ncl/gsun/ • Intended for users with little or no NCL experience • Some programming language knowledge is assumed • Learning by example concept • Starts with basics and builds from there • Provides a set of simple functions written in NCL to be used by new users instead of NCL’s object oriented Graphics interface • The “Beyond the Basics” section covers incorporating FORTRAN into NCL

16. Additional resources for using and learning NCL • NCL users email list • http://ngwww.ucar.edu/ncl-talk/ • Email list devoted to NCL discussion • Read by NCL developers and support staff • Examples page • http://ngwww.ucar.edu/ncl/examples.html • CCSM NCL page for additional examples • http://www.cgd.ucar.edu/csm/support

17. NCL for WRF Model Data • The NCL scripts for plotting WRF model output are our first attempt at producing plots for use in our development efforts. • They can do vertical interpolation (so one can plot data on pressure levels), skew-T, and vertical cross-sections. • They currently plot model output variables plus a few diagnostic variables, such as SLP, dew point temperature, and RH. • Can work with multiple input files and subdomains

18. NCL for WRF Model Data • Advantage: • NCL reads WRF data directly • Can make simple plots quickly • Easy to make difference plots • Disadvantage: • Initial learning may be slow • Array computation may be slow unless using Fortran

19. Downloading • From wrf-model.org web site: http://www.mmm.ucar.edu/wrf/users/download.html • tar file: wrf_ncl.tar • After untar, one finds directory WRF_NCL/README_FIRST README_NCL eh/ em/

20. WRF_NCL/em/ directory make_ncl_fortran make_ncl_fortran.alpha make_ncl_fortran.rhlinux make_ncl_fortran.ibm make_ncl_fortran.sun wrf_user_fortran_util_0.f wrf_user_fortran_util_0.o wrf_user_fortran_util_0.so wrf_user_fortran_util_0_W.c wrf_user_fortran_util_0_W.o wrf_plot.ncl wrf_user_mass.ncl skewt_func.ncl gsn_code.ncl wrf_em_b_wave.ncl wrf_em_hill2d.ncl wrf_em_qss.ncl wrf_em_squall_2d_x.ncl wrf_em_squall_2d_y.ncl wrf_em_sfc.ncl wrf_em_slp.ncl wrf_em_qv.ncl wrf_em_the.ncl wrf_em_real.ncl wrf_em_real_input.ncl Scripts to build fortran shared library Created by fortran build NCL functions and procedures used by the plotting scripts Plotting scripts

21. wrf_plot.ncl • Contains functions and procedures that are used by all ncl plotting scripts: • maps • contour and color-filled plots • vectors • To include it in a ncl script: load “wrf_plot.ncl”

22. skewt_func.ncl • Functions for making skew-T plots • Load near the top of the ncl plotting script

23. wrf_user_mass.ncl • This is where a user may choose to add new variables for plotting • Can be used to obtain native model output variables, or diagnose new variables • Make Fortran calls to routines in wrf_fortran_user_util_0.f • Use existing examples inside the file as templates for adding new variables

24. wrf_fortran_user_util_0.f • Contains Fortran routines for diagnostic calculations • Fortran routines are stubbed with ‘NCLFORTSTART’ and ‘NCLEND’. e.g. C NCLFORTSTART subroutine compute_rh(qv,p,t,rh,nx,ny,nz) implicit none integer nx, ny, nz real qv(nx,ny,nz),p(nx,ny,nz), & t(nx,ny,nz),rh(nx,ny,nz) C NCLEND

25. How to generate shared object file? • makefiles exist to create shared object file from Fortran code for Alpha, Linux, IBM and Sun: e.g. make_ncl_fortran.alpha make_ncl_fortran.linux • Type make_ncl_fortran.alpha wrf_user_fortran_util_0 -> creates wrf_user_fortran_util_0.so • For other machines, edit one of the make files

26. How to run NCL? • Type the following to run (batch example) ncl < wrf_em_real.ncl • To run NCL interactively, type ncl then enter appropriate ncl commands • Output from ncl can be in metacode, postscript, or on the screen

27. WRF-to-VIS5D Wei Wang NCAR/MMM

28. What does it do? • Convert WRF model output data in netCDF to Vis5D format. • Vis5D is a three-dimensional visualization software • Vis5D is free and can be downloaded from http://www.ssec.wisc.edu/~billh/vis5d.html

29. Downloading • From wrf-model.org web site: http://www.mmm.ucar.edu/wrf/users/download.html • tar file: wrf2vis5d.tar • After untar, one finds directory WRF2VIS5D/README eh/ em/

30. WRF2VIS5D/em directory The following files exist in the directory: Makefile README module_wrf_to_v5d_util.F module_wrf_to_v5d_netcdf.F v5df.h wrf_to_v5d.F wrf_v5d_input

31. How to compile and run? • Type the following to compile: make wrf_to_v5d • Edit command line input file: wrf_v5d_input • Type the following to run: wrf_to_v5d wrf_v5f_input vis5d-filename • Type the following to view Vis5D data: vis5d vis5d-filename

32. File wrf_v5d_input -1 ! number of times to put in vis5d file, negative means ignore the times 2000-01-24_18:00:00 U ! variable list for vis5d file, indent one space to skip V ! first five in list are special variables (diagnosed) W THETA TK TC QVAPOR QCLOUD QRAIN RAINC TSK end_of_variable_list Space at the beginning: Not processed

33. File wrf_v5d_input (cont.) wrfout_d01_000000 ! WRF output file name end_of_file_list -1 ! specify v5d vertical grid 0=cartesian, -1=interp to z from lowest h, >1 list levels (z) desired in vis5d file 1 1. 2 2. 3 3. 4 4. 5 5. 6 6. 7 7. 8 8. 9 9. 10 10.

34. RIP4Read/Interpolate/Plot (Version 4) Slides contribution from Dave Gill

35. General Information • Written by Mark Stoelinga of UW • Requires NCAR Graphics low-level routines – freely available from http://ngwww.ucar.edu • Originally written for MM5 input and output, and recently rewritten and generalized to include WRF • Horizontal plots on native model coordinate, pressure, height, q, qe, or PV surfaces • Vertical cross sections on native model coordinate, pressure or log pressure, p, height, q, qe, or PV as coordinate surface

36. General Information (cont) • Skew-T/log p soundings specified at grid points or lat/lon, optional hodographs and sounding quantities • Forward and backward trajectories • Generate input data for Vis5D • Large number of diagnostic fields (> 100) • Allow users to tailor the graphics • Currently works for real-data simulation data only • Detailed documentation

37. Downloading Program tar File • RIP program tar file can be downloaded from http://www.mmm.ucar.edu/wrf/users/download.html • html documentation included

38. Compiling RIP on Your Machine • Uncompress and untar the file: RIP4.TAR.gz • Edit src/Makefile to define paths to netCDF library and include file on your computer: NETCDFLIB and NETCDFINC • make <machine type> (it’ll make suggestions) e.g. make linux compile RIP on a Linux computer

39. RIPDP_WRF • ripdp_wrf: where ‘dp’ stands for Data processing • ripdp_wrf converts WRF netCDF data into RIP input format (format described in the document) • ripdp_wrf puts each variable at each time into a separate file – expect to see LOTS of files

40. Running ripdp_wrf • Set environment variable RIP_ROOT to where RIP is installed and where RIP utility files reside. e.g. setenv RIP_ROOT /users/wrfhelp/RIP4 • Run ripdp_wrf: ripdp_wrf [–n namelist-file] <model_data_name> [basic/all] \ <input_file1 input_file2> namelist-file optional • Make a directory for the files, use that as part of the model_data_name. e.g. ./storm_case/test1

41. RIPDP namelist • Use namelist-file (example in ripdp_sample.in) to add control • select processing times • discard fields if ‘all’ is selected on the command line

42. RIP UIF • UIF : User Input File (example in rip_sample.in) • First section is a list of general parameters (namelist format) • Second section is a Plot Specification Table (or PST)

43. RIP namelist • Use namelist to control • processing times, intervals • title information • text quality on a plot • whether to do time series, trajectory, or to write output for Vis5D • Full explanation for namelist variables is available in the user document

44. RIP UIF &userin .... / &trajcalc .... / =============================================== --------- Plot Specification Table ------------ =============================================== Plot specification line (PSL) PSL: plot spec settings (PSS) PSL: PSSs =============================================== namelist frame specification group(FSG)

45. RIP PST FSG PSL • PST – Plot Specification Table • First line is “====“, next 2 lines ignored • Each group separated by subsequent “===“ is a FSG (Frame Specification Group) • Each line within an FSG is a PSL (Plot Specification Line) • An FSG with 3 PSLs will have 3 plots on one frame

46. RIP PSS • Each PSL contains several PSSs (Plot Specification Settings) (see example next) • keyword=value[,value,value] • keyword is a 4-char identifier • All PSSs within a PSL are separated by “;” • Last PSS on a PSL has no “;” • “>” at the end of the line means the PSL continues • Comments require a “#”

47. An example of PST ======================================================== feld=tmc; ptyp=hc; vcor=s; levs=b1; cint=2; cmth=fill;> cosq=-32,light.violet,-24,violet,-16,blue,8,green, > 0,yellow,8,red,16,orange,24,brown,32,light.gray feld=slp; ptyp=hc; cint=2; linw=2 feld=uuu,vvv; ptyp=hv; vcmx=-1; colr=white; intv=5 feld=map; ptyp=hb feld=tic; ptyp=hb ======================================================== * Bold letters indicate ‘keywords’

48. Running RIP • Edit the UIF (rip-execution-name.in) • Type the following to run: rip [-f] model-data-set-name rip-execution-name • model-data-set-name is from RIPDP_WRF • rip-execution-name is unique name, for output, metacode and UIF e.g. rip-execution-name.cgm • View the .cgm file using NCAR Graphics utility idt rip-execution-name.cgm

49. Other Notes • Appendix A contains a list of keywords for PSS • Appendix B has a long list of fields that can be plotted by RIP • New fields may be added • Currently works with wrfout files only, and with real-data