Application examples >
ContourPlot example 8
This example can be created using HLU C library calls, HLU FORTRAN
library calls, or NCL. It demonstrates how to read data from a netCDF
file and create a series of contour plots from the data. The example
shows a vertical profile of temperature for longitudes separated by 5
degrees. The names of the example codes that create
this plot are cn08c.c, cn08f.f, and cn08n.ncl.
View this animation.
This module discusses how to create the previous plot using HLU
function calls and NCL. This module also shows how to read netCDF
data from a file and produce a series of contour plots. This example
reads a subset of temperature data from a netCDF file, creates a
contour plot of the data, and then repeats this process to produce
several frames in a sequence of time steps. There is no resource file
for this example, as all the resources are set in the source code.
A detailed discussion of how this example works appears in its
The HLU C program that generates this plot is called cn08c.c
The HLU FORTRAN program that generates this plot is called cn08f.f
The NCL script that generates this plot is called
The data for this plot is from a netCDF file called contour.cdf.
This example data file contains several geophysical variables including
a four-dimensional temperature variable, T. A subset of this variable is
read from the netCDF file along with latitude and longitude coordinate
variables for each time step.
The data file is located in your NCAR Graphics data directory in a
subdirectory called "cdf". You can get the name of the data directory
by typing "ncargpath data" at your shell prompt. If you have netCDF
installed on your system, then you can change directory to where the
netCDF file resides and type "ncdump -h contour.cdf" to view the
header information for this data file.
The examples are installed in the following locations:
The netCDF data file is installed in the following location:
You can copy this example and run it by typing "ng4ex
cn08f", or "ng4ex cn08n". A copy of the source file and resource file
will be placed in your current working directory. The source code will
be compiled and automatically run for you. You must have the netCDF
installed on your system in order to compile the C or FORTRAN version
of this example.
You can view the output NCGM file using the NCAR Graphics ctrans
utility. (For example, to view the file generated from cn08n.ncl,
type "ctrans cn08n.ncgm".)