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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
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. ------------------------------------------------------------------------- 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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