NCL Website - A Tour of Features, Functions, and Capabilities

1. Tour of NCL Website www.ncl.ucar.edu Modified by R. Grotjahn 2016 03 04

3. NCL capabilities: • Functions • Visualization (many graphics, map overlays, 3-D, etc.) • Mathematical (divergence, regridding, EOFs, filtering, etc.) • Statistical (correlation, spectra, wavelets, kmeans, etc.) • Earth-science specific (omega, vorticity, PV, crop variables, heat stress, Taylor diagram, etc.) • Computational (array creation, file conversion, etc.) • Support • Examples (very many, illustrative, very useful guides) • Reference listings of functions • Manuals, training exercises, and presentations • FAQs (searchable)

4. NCL capabilities: • See overview: • http://www.ncl.ucar.edu/overview.shtml • Handles many output formats • publication-ready plots • built-in capabilities, especially for earth science (>600 functions) • supports Fortran and C externals

5. NCL routines: • use specifically with climate and model data • computing empirical orthogonal functions, Fourier coefficients, singular value decomposition, averages, standard deviations, sin, cosine, log, min, max, etc. • retrieving and converting date information • drawing primitives (lines, filled areas, and markers), wind barbs, weather map symbols, isosurfaces, and other graphical objects • robust file handling • 1-dimensional, 2-dimensional, and 3-dimensional interpolation, approximation, and regridding • facilitating computer analysis of scalar and vector global geophysical quantities (most are based on the package known as Spherepack) • retrieving environment variables and executing system commands

6. NCL capabilities: • It can do a lot because it is built on many long-established libraries both graphical and mathematical

7. NCL Examples: • Applications page www.ncl.ucar.edu/Applications/ • Great starting place to find the capability you seek. • Many datasets available as well

8. NCL Examples: Data Analysis (cont.) • Applications page links: • Graphics • Cylindrical equidistant maps http://www.ncl.ucar.edu/Applications/cylineq.shtml • Panel plots http://www.ncl.ucar.edu/Applications/panel.shtml • WRF model http://www.ncl.ucar.edu/Applications/wrf.shtml • Vectors http://www.ncl.ucar.edu/Applications/vector.shtml

9. NCL Examples: • Applications page links: • Datasets • File I/O http://www.ncl.ucar.edu/Applications/list_io.shtml • Shape files http://www.ncl.ucar.edu/Applications/shapefiles.shtml • Topography http://www.ncl.ucar.edu/Applications/topo.shtml • Daymethttp://www.ncl.ucar.edu/Applications/daymet.shtml • PRISM http://www.ncl.ucar.edu/Applications/prism.shtml

10. NCL FAQs: • Link: http://www.ncl.ucar.edu/FAQ/ • Useful learning tool, search it if you cannot find an example that does what you want to do • Code snippets provided • Categorized, but search is usually more effective • You can ask your own questions.

11. NCL Functions: • Functions are listed several ways: • alphabetically: http://www.ncl.ucar.edu/Document/Functions/list_alpha.shtml • by category grouping: http://www.ncl.ucar.edu/Document/Functions/ • by function type grouping: http://www.ncl.ucar.edu/Document/Functions/list_type.shtml • via applications examples: http://www.ncl.ucar.edu/Applications/ • Also: • Graphics resources (like ws, vc, cn, etc.): http://www.ncl.ucar.edu/Document/Graphics/Resources/ • but these are specialized, many are beyond the level of this class

12. NCL color tables: • Link: http://www.ncl.ucar.edu/Document/Graphics/color_tables.shtml • Create your own http://www.ncl.ucar.edu/Document/Graphics/create_color_table.shtml • Use named colors http://www.ncl.ucar.edu/Document/Graphics/named_colors.shtml • Examples: (rainbow, +/-, etc.)

13. NCL Other Popular Links: • See: http://www.ncl.ucar.edu/links.shtml • Markers: http://www.ncl.ucar.edu/Document/Graphics/marker_styles.shtml • Dashed/line patterns: http://www.ncl.ucar.edu/Document/Graphics/dash_patterns.shtml • Font tables: http://www.ncl.ucar.edu/Document/Graphics/font_tables.shtml

14. NCL Other Tools: • Main link: http://www.ncl.ucar.edu/Document/Tools/ • Conversion between ncl and some other formats, notably GRIB#, HDF_, shapefiles: http://www.ncl.ucar.edu/Document/Tools/ncl_convert2nc.shtml • Wrapper to include Fortran or C functions in your NCL program: http://www.ncl.ucar.edu/Document/Tools/WRAPIT.shtml • graphics x-window viewer idt: http://www.ncl.ucar.edu/Document/Tools/idt.shtml • Links to other tools such as: • ImageMagick: for conversion between graphics types (e.g. ps png) • mpeg2encode: to create a mpeg from a multi-frame ps file

15. NCL in python: • PyNGL and PyNIO modules • PyNGL (Python interface to NCL’s graphics library) http://www.pyngl.ucar.edu/ • PyNIO (Python interface to NCL’s file I/O capabilities) http://www.pyngl.ucar.edu/Nio.shtml • Training via exercises: http://www.pyngl.ucar.edu/Training/Exercises/

16. NCL Support: • Common error messages: http://www.ncl.ucar.edu/Document/Language/error_messages.shtml • Main email support link: http://www.ncl.ucar.edu/Support/email_lists.shtml • ncl-talk: http://mailman.ucar.edu/mailman/listinfo/ncl-talk • other pages for ncl installation • questions about PyNGL and PyNIOhttp://mailman.ucar.edu/mailman/listinfo/pyngl-talk

17. NCL Tutorials: • General link: http://www.ncl.ucar.edu/Training/Workshops/links.shtml • NCAR Powerpoints: http://www.ncl.ucar.edu/Training/Workshops/Scripts/ • Example scripts (contouring, maps, overlays, vectors, shapefiles,…): http://www.ncl.ucar.edu/Training/Workshops/Scripts/ • Step-by-step Graphical exercises: http://www.ncl.ucar.edu/Training/Workshops/Exercises/ • Sample data files: http://www.ncl.ucar.edu/Applications/Data/

18. NCL End of overview: • Next: • NCL-04_Shea-Brownrigg_Introduction.pdf • Learn the basics of the language, make example plots.