NetCDF group,
Our EPIC software for oceanographic data provides graphical display and data
field manipulation for multi-dimensional netCDF files (up to 4-dimensions). We
have been using this software on Unix and VMS for about a year. At present, we
have:
* a data file I/O library (epslib, which is layered on top of the netCDF
library).
* epslib allows transparent access to multiple data file formats
* netCDF file calculator and data editor
* time series spectral analysis package (spectra, coherences, time and
frequency domain eofs, rotary spectra, etc)
This software was developed as an expansion to our VAX/VMS based EPIC data
management, display and analysis system for observational oceanographic time
series and hydrographic data. It was developed on Sun/Unix and is supported
for Sun/Unix, DEC/Ultrix and VAX/VMS, and is part of our transition from VMS to
Unix. Our VAX EPIC software, about 100 programs for oceanographic display and
analysis, will be ported to Unix as well, and we are quite interested in
coordinating with others who may be developing oceanographic software for use
with netCDF files. PPLUS is a commercial graphics package, but the EPIC
software is public domain and freely available, and we are interested in
exchanging information with others who have similar software or software needs.
We are very interested in collaborating with others who are interested in a
implementation of netCDF format for this type of data.
Our netCDF calculator includes an interactive data manipulation, editing, and
display capability for our EPIC System style of netCDF files. It is linked
with the PPLUS graphics package, which we use here at PMEL. With this
combination, you can extract 1-d, 2-d, etc slabs from a 4-d netCDF file written
with EPIC system conventions, do algebraic manipulations with the data fields
and/or display the data, all in an interactive environment. Calculated data
fields can be written out as another netCDF file. This software is supported
for Unix and for VMS (it was written for Unix and ported to VMS). It was
developed for PMEL under contract with Dr. Donald Denbo at Battelle NW. Dr.
Denbo also wrote the PPLUS graphics package. The netCDF calculator software is
public domain. It can be used without being linked to the PPLUS graphics
package, and I have put it into our anonymous ftp directory.
Our data file I/O library, epslib, is layered onto the netCDF library, and
provides data format independent I/O routines. Application programs call a
"format independent layer" of routines, which in turn, calls a "format
dependent layer" for each of the supported data formats. Supported formats
presently include netCDF files and Classic EPIC data files (VAX binary files).
A new format can be added by writing 8 new "format dependent" subroutines to
support I/O for the new format. The EPIC epslib is written in ANSI standard C,
is callable callable from C or from Fortran, and is supported for VAX/VMS,
Sun/Unix and DEC/Ultrix. EPIC system compatible files can also be written
directly with the netCDF library routines. For us, epslib provides
"standardized" (EPIC standard) support for observational oceanographic
attributes and for multiple data formats. It provides us with a gentle
transition from VMS and VMS binary 1-d files to Unix, netCDF and
multidimensional files.
It is possible to use our PPLUS and netCDF calculator function with netCDF
files created with either the netCDF libraries or with our own epslib, provided
that the data files are EPIC system compatible. This is described in the file
netCDF.doc in our anonymous FTP directory. At present, 4 PMEL programmers are
coding with our new epslib. However, this rather new system at PMEL is still
evolving. If the netCDF group or UCAR standardizes on a time axis format or
formats, then we will implement these. We will probably retain upward
compatibility with our original netCDF implementation as well as using the
netCDF standard as our standard. We are very interested in cooperating with
efforts to standardize. For example, our present epslib implementation utilizes
a variable definition file (epic.key), and this dependence could be (and
probably will be) removed from our netCDF file format requirements. We are
already using the netCDF units standard.
The PPLUS graphics package is sold by Dr. Denbo's company PPLUS GRAPHICS (PO
Box 4, Sequim, WA 98382; Don's internet address is dwd@xxxxxxxxxxxxx). PPLUS is
supported for many Unix systems and for VMS, and is a general purpose
scientific graphics package, which will read most standard ascii or binary
files, as well as netCDF files. It includes an X windows driver, PostScript
translator, and others (e.g. Tektronix, Regis, Versatec, HP, etc). It is in
use at many oceanographic institutions (PMEL, Harvard, WHOI, etc). If you are
interested, please contact Don Denbo (cost is $1000 for an institution).
Our anonymous ftp directory is (csg@xxxxxxxxxxxx, 192.68.151.12), directory
[anonymous.netcdf]. There is a readme.doc file in the directory, and a
netCDF.doc file with some information about what a netCDF file must have to be
EPIC system compatible. It is a VAX, so compressed tar files are named
something like ppl.tar_Z.
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Nancy Soreide Tel: 206-526-6728
NOAA/Pacific Marine Environmental Laboratory Fax: 206-526-6744, 6815
7600 Sand Point Way Northeast Internet: nns@xxxxxxxxxxxx
Seattle, WA 98115 OMNET: TAO.PMEL
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