The submitted files related to AVS module read_netcdf, in addition 
to this README file, are:
         filename                    contents
         --------                    --------
         Makefile             standard Unix makefile
         read_netcdf.c        C source code
         read_netcdf.txt      module description in man page form
         small.cdf            sample netCDF binary file

It is assumed that prospective users have the netCDF library available on 
their system.

     The purpose of submitting this module to the International AVS Center 
is to provide a working example of a module that reads a netCDF data file 
to serve as a template for developing similar modules.  The submitted module 
is currently used to read data generated by an ocean circulation modeling 
application.  The module reads one data variable (i.e., salinity) at a
particular time step and the necessary data for computing the 3-dimensional 
irregular coordinates used by the model.
AVS Local Modules                                             read netcdf(6)

NAME
     read netcdf - read a netCDF file that follows specific conventions

SUMMARY
     Name          read netcdf
     Type          data	
     Inputs        none
     Outputs       field 3D scalar float 3-coord irregular
     Parameters	   Name              Type       Default   Min    Max
                   Read netCDF File  browser	*.cdf
                   time record	     typein     0         0      1000
DESCRIPTION
     The read netcdf module is a working example of a module that can read 
     netCDF files.  This version can only read netCDF files that contain 
     specific dimension, variable, and attribute names.  Also, the coordinate 
     values for the irregular field output are computed in a way that is data 
     specific.  See LIMITATIONS below for details.
     
PARAMETERS
     Read netCDF File
          A file browser that displays filenames with the .cdf extension.

     time record
          Integer typein that defines which time record of data to read.
          By default, time record 0 (i.e., first record) is read.  Only
          one time record is read.  The maximum time record number is 
          currently set to 1000.

EXAMPLE	
     The following network converts netCDF data into an AVS field, displays
     the contents of the new field, and	gives the person the option of
     writing the new AVS field permanently to disk. 

                            READ NETCDF
                                |
                                |--------------|
                                |              |
                           PRINT FIELD    WRITE	FIELD
LIMITATIONS
     The netCDF files to be read by this version of read netcdf must contain
     the following dimension names:  xpos, ypos, zpos, and time, where the 
     size of dimension time is declared as UNLIMITED.  The following variables
     must be in the file:  float variables sigma(zpos), x(ypos,xpos), 
     y(ypos,xpos), and depth(ypos,xpos) and short variables elev(time,ypos,xpos)
     and salt(time,zpos,ypos,xpos).  Variables elev and salt must have the 
     following float attributes: scale_factor and add_offset, where the scale 
     factor is to be multiplied first and then the offset added to the data.

     The data portion of the AVS field output is the data from variable salt.
     The X and Y coordinates are variables x and y scaled by a factor of 1/4000.
     The Z coordinates are calculated from variables sigma, depth and elev as 
     follows:
                 Z = sigma*(depth + elev) + elev
SEE ALSO
     Unidata Program Center, 1991, NetCDF User's Guide: An Interface for Data 
     Access, University Corporation for Atmospheric Research, Boulder, CO.

     Wright, E.L., 1992, An Example of Interfacing AVS and NetCDF:  U.S. 
     Geological Survey Open-File Report 92-332.

Release	3.0			    AVS			     read netcdf(6)