MITgcm_contrib/netcdf_matlab_examples/README.txt


Examples:  NetCDF & MatLAB
==========================

These directories contain examples of MatLAB commands for reading,
creating, and modifying NetCDF files.  All the scripts use Chuck
Denham's MatLAB package which can be obtained at:

  "MexCDF and NetCDF Toolbox For Matlab-5&6"
  http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html

and must first be installed.


The NetCDF files generated here are intended for use with Ingrid:

  http://ingrid.mit.edu/

As a result, they approximately follow the simple COARDS convention
which is described at:

  http://www.unidata.ucar.edu/packages/netcdf/conventions.html
  http://ferret.wrc.noaa.gov/noaa_coop/coop_cdf_profile.html


The key items for the use of NetCDF files within Ingrid are:

  1) In order to work with the Ingrid "plot land" option, dimensions
     should have units of "degree_east" and "degree_north" as, for
     example, specified by:

       nc{'lon'}.units = 'degree_east';
       nc{'lat'}.units = 'degree_north';

     The actual dimension names (eg. "lat" or "Y") are unimportant.

  2) It is generally a good idea to set the "gridtype" to 1 or 0 to
     indicate that the coordinate "wraps" or not.  The gridtype
     attribute allows Ingrid to, for instance, plot longitudinal data
     over "wrapped" ranges such as -100 to 500deg.  The attribute can
     be set using commands such as:

       nc{'X'}.gridtype = ncint(1);
       nc{'Y'}.gridtype = ncint(0);

  3) Ingrid does seem to correctly handle the "_FillValue" attribute
     and it can be set using a MatLAB command such as:

       nc{ idu }.FillValue_ = ncdouble(-9999.0);

     [ Note how the "_" character is moved to the end of the attribute
       name since MatLAB cannot correctly handle variable names with a
       leading underscore. ]
1
2	Examples: NetCDF & MatLAB
3	==========================
4
5	These directories contain examples of MatLAB commands for reading,
6	creating, and modifying NetCDF files. All the scripts use Chuck
7	Denham's MatLAB package which can be obtained at:
8
9	"MexCDF and NetCDF Toolbox For Matlab-5&6"
10	http://woodshole.er.usgs.gov/staffpages/cdenham/public_html/MexCDF/nc4ml5.html
11
12	and must first be installed.
13
14
15	The NetCDF files generated here are intended for use with Ingrid:
16
17	http://ingrid.mit.edu/
18
19	As a result, they approximately follow the simple COARDS convention
20	which is described at:
21
22	http://www.unidata.ucar.edu/packages/netcdf/conventions.html
23	http://ferret.wrc.noaa.gov/noaa_coop/coop_cdf_profile.html
24
25
26	The key items for the use of NetCDF files within Ingrid are:
27
28	1) In order to work with the Ingrid "plot land" option, dimensions
29	should have units of "degree_east" and "degree_north" as, for
30	example, specified by:
31
32	nc{'lon'}.units = 'degree_east';
33	nc{'lat'}.units = 'degree_north';
34
35	The actual dimension names (eg. "lat" or "Y") are unimportant.
36
37	2) It is generally a good idea to set the "gridtype" to 1 or 0 to
38	indicate that the coordinate "wraps" or not. The gridtype
39	attribute allows Ingrid to, for instance, plot longitudinal data
40	over "wrapped" ranges such as -100 to 500deg. The attribute can
41	be set using commands such as:
42
43	nc{'X'}.gridtype = ncint(1);
44	nc{'Y'}.gridtype = ncint(0);
45
46	3) Ingrid does seem to correctly handle the "_FillValue" attribute
47	and it can be set using a MatLAB command such as:
48
49	nc{ idu }.FillValue_ = ncdouble(-9999.0);
50
51	[ Note how the "_" character is moved to the end of the attribute
52	name since MatLAB cannot correctly handle variable names with a
53	leading underscore. ]