SCD User Briefing NCL and PyNGL Visualization for the Geosciences Don Middleton with presentation material developed by Luca Cinquini, Mary Haley, Fred

Supercomputing • Communications • Data

NCAR Scientific Computing Division

SCD User Briefing NCL and PyNGL

Visualization for the Geosciences

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


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


Section Head, Visualization & Enabling Technologies

January 11, 2005

85th AMS Annual MeetingJanuary 9-14, 2005



NCL and PyNGLVisualization for the Geosciences

NCL and PyNGLVisualization for the Geosciences



TopicsTopics 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



What is NCL?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



NCL File I/ONCL 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



NCL Data ProcessingNCL Data ProcessingOver 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



NCL VisualizationNCL 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



GSUN: interface to NCL visualizationGSUN: 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



What is PyNGL?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



import Nglfrom 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 = lonres.sfYArray = lat# Tickmarks displayed by default.# Size maximized by default.

# Draw contours over a mapcontour = 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

Data from the MECCA Project

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

Wind velocity vectorsWind velocity vectors



Courtesy Sylvia Murphy, NCAR CGD

From John Ertl, FNMOC

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

Climate division data courtesy Mark Stevens, NCAR CGD

Courtesy Mark Stevens, NCAR CGD



Contouring on arbitrary triangular meshes

Image from Jonathan Shewchuk, author of Triangle

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

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



Future PyNGL plansFuture 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



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.htmlhttp://ngwww.ucar.edu/ncl/download.html



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Documents

SCD User Briefing NCL and PyNGL Visualization for the Geosciences Don Middleton with presentation material developed by Luca Cinquini, Mary Haley, Fred