ContourPlot example 7

Creating contour plots of NetCDF geo-potential height data

This example demonstrates how to read data from a NetCDF file and create a series of contour plots from the data. This example was created using NCL commands. The name of the example script is cn07n.ncl.

Discussion

This module discusses how to create this plot using NCL commands. 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 geo-potential height 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.

A detailed discussion of how this example works appears in its source code.

Creating the plot using HLU C library calls

Currently, the HLU C code has not been written for this example.

Creating the plot using HLU FORTRAN library calls

Currently, the HLU FORTRAN code has not been written for this example.

Creating the plot using NCL

The NCL script that generates this plot is called cn07n.ncl.

The data

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 geo-potential height variable, Z. A subset of this variable is read from the netCDF file along with latitude and longitude coordinate variables for each time step.

This data file is located in your NCAR Graphics data directory. You can get the name of this directory by typing "ncargpath data" at your shell prompt. Change to this directory and then type "ncdump -h contour.cdf" to view the header information for this data file and see all the variables and data attributes.

How to run this example

This example is installed in the following location:

$NCARG_LIB/ncarg/nclex/contourplot/cn07n.ncl
You can copy this example and run it by typing "ng4ex cn07n". A copy of the NCL script will be placed in your current working directory and run automatically for you.

You can view the output NCGM file using the NCAR Graphics ctrans utility. (Type "ctrans cn07n.ncgm".)


Quick Start Guide Control Panel

NG4 Home, Index, Examples, Glossary, Feedback, QSG Contents, QSG WhereAmI?


$Revision: 1.5 $ $Date: 1995/07/26 23:24:34 $