1. SCD User Briefing NCL and PyNGL Visualization for the Geosciences Don Middleton with presentation material developed by Luca Cinquini, Mary Haley, Fred Clare - and many project collaborators NCAR Scientific Computing Division Section Head, Visualization & Enabling Technologies January 11, 2005 Don Middleton with presentation material developed by Luca Cinquini, Mary Haley, Fred Clare - and many project collaborators NCAR Scientific Computing Division Section Head, Visualization & Enabling Technologies January 11, 2005 85th AMS Annual Meeting January 9-14, 2005

2. NCL and PyNGL Visualization for the Geosciences

3. Topics  NCAR Command Language (NCL)  GSUN (NCL visualization interface)  PyNGL  Example codes and visualizations  Future plans  NCAR Command Language (NCL)  GSUN (NCL visualization interface)  PyNGL  Example codes and visualizations  Future plans

4. What is NCL?  NCAR Command Language  Scripting language, powerful in 3 areas: -File input/output -Data processing -Publication-quality visualizations Runs on Linux, MacOSX, Solaris, IRIX, AIX, OSF1, Cygwin

5. NCL File I/O Based on the netCDF model: Read/write netCDF, HDF4, ASCII, binary Reads GRIB, including ECMWF complex coefficients  One interface for several data formats Based on the netCDF model: Read/write netCDF, HDF4, ASCII, binary Reads GRIB, including ECMWF complex coefficients  One interface for several data formats

6. NCL Data Processing Over 600 functions and procedures: Spherical harmonic based calculations Scalar and vector regridding Vertical interpolation, including hybrid coordinates to pressure level Spectral/cross spectral and wavelet analysis Can access Fortran and C routines directly from NCL Over 600 functions and procedures: Spherical harmonic based calculations Scalar and vector regridding Vertical interpolation, including hybrid coordinates to pressure level Spectral/cross spectral and wavelet analysis Can access Fortran and C routines directly from NCL

7. NCL Visualization Publication-quality visualizations: Contour, line, vector, streamline, map Customization: hundreds of options Output to X11, PostScript, PDF Lots of examples Publication-quality visualizations: Contour, line, vector, streamline, map Customization: hundreds of options Output to X11, PostScript, PDF Lots of examples

8. GSUN: interface to NCL visualization  “Getting Started Using NCL”  Successful collaboration w/CCSM users  User-friendly, customized visualization functions  Extensive documentation and examples  Interface of choice for NCL visualization  GSUN used as a model for PyNGL  “Getting Started Using NCL”  Successful collaboration w/CCSM users  User-friendly, customized visualization functions  Extensive documentation and examples  Interface of choice for NCL visualization  GSUN used as a model for PyNGL

9. What is PyNGL?  Python NCL Graphics Library  Python version of popular GSUN interface  Same publication-quality graphics as NCL  Utilizes existing Python modules  Multiple output formats  Extensive documentation  Python NCL Graphics Library  Python version of popular GSUN interface  Same publication-quality graphics as NCL  Utilizes existing Python modules  Multiple output formats  Extensive documentation

10. import Ngl from Scientific.IO.NetCDF import * # Open the NetCDF file. nfile = NetCDFFile("meccatemp.cdf","r") # Get lat/lon/temperature variables. lat = nfile.variables["lat"][:] lon = nfile.variables["lon"][:] T = nfile.variables["t"][0,:,:] # Open a PS workstation. wks = Ngl.open_wks("ps","mecca") # Set contour & scalar field resources. res = Resources() res.sfXArray = lon res.sfYArray = lat # Tickmarks displayed by default. # Size maximized by default. # Draw contours over a map contour = Ngl.contour_map(wks,T,res) Ngl.end() PyNGL load "gsn_code.ncl" begin ; Open the NetCDF file. nfile = addfile("meccatemp.cdf","r") ; Get lat/lon/temperature variables. lat = nfile->lat lon = nfile->lon T = nfile->t(0,:,:) ; Open a PS workstation. wks = gsn_open_wks("ps","mecca") ; Set contour & scalar field resources. res = True res@sfXArray = lon res@sfYArray = lat res@pmTickMarkDisplayMode = “Always” res@gsnMaximize = True ; Draw contours over a map. contour = gsn_contour_map(wks,T,res) end GSUN

11. Data from the MECCA Project

12. From a presentation of Jeff Kiehl (NCAR) and Tim Schneider (NOAA)

13. Wind velocity vectors Data from the MECCA Project

15. Courtesy Sylvia Murphy, NCAR CGD

16. From John Ertl, FNMOC

17. Based on a visualization of Joel Norris (Scripps) using synthetic data

18. Climate division data courtesy Mark Stevens, NCAR CGD

19. Courtesy Mark Stevens, NCAR CGD

20. Contouring on arbitrary triangular meshes Image from Jonathan Shewchuk, author of Triangle

21. Grid from Tom Gross, NOAA/NOS/CSDL/MMAP

22. Data and grid from Tom Gross, NOAA/NOS/CSDL/MMAP

23. Future PyNGL plans  Pythonize NCL’s powerful I/O module and climate and interpolation functions  Add more functionality and examples  Pythonize NCL’s powerful I/O module and climate and interpolation functions  Add more functionality and examples

24. PyNGL/NCL Documentation: http://www.pyngl.ucar.edu/ http://ngwww.ucar.edu/ncl/ PyNGL/NCL talk email lists: http://www.pyngl.ucar.edu/pyngl-talk/ http://ngwww.ucar.edu/ncl/ncl-talk/ Download PyNGL/NCL: http://www.pyngl.ucar.edu/download.html http://ngwww.ucar.edu/ncl/download.html

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