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SCD User Briefing NCL and PyNGL Visualization for the Geosciences

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

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SCD User Briefing NCL and PyNGL Visualization for the Geosciences

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  1. SCD User BriefingNCL and PyNGLVisualization for the Geosciences 85th AMS Annual Meeting January 9-14, 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

  2. NCL and PyNGLVisualization for the Geosciences

  3. Topics • 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

  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

  7. NCL Visualization 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

  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

  10. PyNGL GSUN 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() 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

  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

  14. 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

  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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