Re: netcdf and web: visualization

• To: netcdfgroup@xxxxxxxxxxxxxxxx
• Subject: Re: netcdf and web: visualization
• From: hankin@xxxxxxxxxxxxxxxxxxx (Steve Hankin)
• Date: Thu, 4 Apr 1996 15:32:13 -0800

Hi All,

Really cool!

Dan Kelley, Jon Meek, Rich Signell, and William Weibel have been suggesting
some fantastic ideas! On their inspiration I decided to try a test hook up: how
to make Ferret into a Web application to analyze and visualize NetCDF files
directly from the Web. It works like a charm. The (very short) nitty gritty of
setting it up is below. Also some test sites with NetCDF data.

This illustrates some of the power of NetCDF as a file standard. It also
illustrates some of its limitations - especially regarding the lack of
standardization ... an opportunity to keep up the chatter on the standards
efforts:
        http://www.unidata.ucar.edu/packages/netcdf/conventions.html

        - steve

===========================================================================


Here are some test sites where I had instant success with this technique:

        http://ferret.wrc.noaa.gov/data
                ("test.nc" is deliberately small for testing)
           try
                yes? shade sst[t=15-jan]

        http://ferret.wrc.noaa.gov/fbin/climate_server
                has a number of research-quality climate data sets with
                fast access to data subsets - select any 1,2,3 or 4
                dimensional region and ask for a NetCDF file.


        http://www.cdc.noaa.gov
                The Climate Diagnostics Lab has an extensive NetCDF archive.
                Sample navigation: select "Data Archives Overview"
                then "a collection of metadata" then "coads1" then
                "sea_level_pressure" then "slp.ltm.nc" (ltm refers to "Long
                Term Mean" so this is a small file). There's lots of data
                and it's well documented but most of the files are pretty
                large for this type of browsing.

        http://rainbow.ldgo.columbia.edu/datacatalog.html
                Lamont-Doherty Earth Observatory of Columbia University is
                another big NetCDF data supplier. For a test navigation try
                Data Library Tour->Finding a dataset->Datasets by Source->
                Datasets by Source->CLIMAP->Last Glacial Maximum->Temperature->
                Data Files->netCDF format


=============================================================================

Here's how I to set up (hacked) to run Ferret as a Web helper:

        1) in my home directory I created file netcdf_via_ferret with these
           lines:

                #! /bin/csh
                source /home/r3/tmap/bin/ferret_paths
                echo use \"$argv[1]\" >! $HOME/.ferret
                echo show data >> $HOME/.ferret
                /usr/bin/X11/xterm -e $FER_DIR/bin/ferret

        Note: i) these paths are for OSF ... slight diffs on other systems
             ii) make sure to    "chmod +x netcdf_via_ferret"
            iii) thie script over-writes your .ferret file


        2) in ~/.mailcap add the line

                application/x-netcdf; /home/rogue/hankin/tmp/dump_that_file %s

        3) in ~/.mime.types add the line

                application/x-netcdf            nc cdf

You'll probably have to start up a fresh copy of your browser (Netscape) so it
rereads the .mailcap information.

==============================================================================

Of course, all this assumes that Ferret is already installed on your system. If
it is not you can download it from

        http://www.pmel.noaa.gov/ferret/home.html
or      ftp://abyss.pmel.noaa.gov/pub/


-- 

                |  NOAA/PMEL               |  ph. (206) 526-6080  
Steve Hankin    |  7600 Sand Point Way NE  |  FAX (206) 526-6744
                |  Seattle, WA 98115-0070  |  hankin@xxxxxxxxxxxxx