Using GrADS to retrieve HYCOM data

Kevin M Levey klevey at CUSTOMWEATHER.COM
Wed May 6 12:32:15 EDT 2009


Hi Mark,

Make sure you are using GRADSDODS from the command line and NOT
gradsnc or gradsc (GRads versions < 2) or simply "grads" using version 2

Version 1.91:

I can open your file using gradsdods as follows:

weather:fweather1 ~ > gradsdods

Grid Analysis and Display System (GrADS) Version 1.9.0-rc1
Copyright (c) 1988-2007 by Brian Doty and IGES
Center for Ocean-Land-Atmosphere Studies (COLA)
Institute for Global Environment and Society (IGES)
GrADS comes with ABSOLUTELY NO WARRANTY
See file COPYRIGHT for more information

Config: v1.9.0-rc1 32-bit little-endian readline sdf/xdf netcdf dap
dap-stn lats athena printim

Issue 'q config' command for more information.

Landscape mode? (no for portrait):
GX Package Initialization: Size = 11 8.5
ga->  http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
Unknown command: http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
ga-> sdfopen http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
Scanning self-describing file:  http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
SDF file http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
  is open as file 1
LON set to 74.16 434.08
LAT set to -78.64 46.8781
LEV set to 0 0
Time values set: 2009:5:5:0 2009:5:5:0
ga->

Not using gradsdods is a common mistake here.

Using version 2.0

weather:fweather1 /usr/local/grads2/Contents > ./grads

               Welcome to the OpenGrADS Bundle Distribution
               --------------------------------------------

For additional information enter "grads --help".

Starting "/usr/local/src/grads-2.0.a5.oga.4/Contents/Linux/Versions/
2.0.a5.oga.4/x86_64/grads   " ...


Grid Analysis and Display System (GrADS) Version 2.0.a5.oga.4
Copyright (c) 1988-2008 by Brian Doty and the
Institute for Global Environment and Society (IGES)
GrADS comes with ABSOLUTELY NO WARRANTY
See file COPYRIGHT for more information

Config: v2.0.a5.oga.4 little-endian readline printim grib2 netcdf hdf4-
sds opendap-grids,stn athena geotiff
Issue 'q config' command for more information.
Loading User Defined Extensions table </usr/local/src/grads-2.0.a5.oga.
4/Contents/Linux/Versions/2.0.a5.oga.4/x86_64/gex/udxt> ... ok.
Landscape mode? ('n' for portrait):
GX Package Initialization: Size = 11 8.5
ga->  sdfopen  http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
Scanning self-describing file:  http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
SDF file http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
  is open as file 1
LON set to 74.16 434.08
LAT set to -78.64 46.8781
LEV set to 0 0
Time values set: 2009:5:5:0 2009:5:5:0
E set to 1 1
ga->

As you can see, I can open your file just fine here too!

Cheers
Kevin

On May 6, 2009, at 05/06/09 - 8:34 AM, Mark Hess wrote:

> Think I still must be doing something wrong and/or missing a few
> important concepts.  Here's what I get:
>
> ga-> sdfopen http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
> Scanning self-describing file:
> http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
> gaopnc error: nc_open failed to open file
> http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc
> read_metadata: gaopnc failed
> gadsdf: Couldn't ingest SDF metadata.
>
> Perhaps I need to work on creating a .ctl file?  Any help with that
> is appreciated.
>
> Thanks,
>
> Mark
>
>
> ----- Original Message -----
> From: James T. Potemra
> To: GRADSUSR at LIST.CINECA.IT
> Sent: Tuesday, May 05, 2009 5:29 PM
> Subject: Re: Using GrADS to retrieve HYCOM data
>
> Hi Mark:
>
> Your variable constraints look more like Matlab syntax to me.  If you
> simply use sdfopen http://...... .nc (truncate
> everythins from the ? to the end) it should work.  You'll then have
> access to the entire data file and can just
> 'set x 1500 2300', 'set y 1750 2169', and so on, then 'd mld'
>
> Jim
>
> Mark Hess wrote:
> > Can anyone tell me what I am doing wrong here?  At this point I'm
> just
> > trying to get a file off of the HYCOM server.  I used the server
> > http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc.html
>  to
> > generate the URL string below, but am obviously missing something
> > quite basic (I'm an inexperienced GrADS user and brand new to
> > OPeNDAP). Will I need to create a custom .ctl file to access and
> > display these data or am I simply using the sdfopen command
> incorrectly?
> >
> > I am running GrADS version 2.0.a3.  My command and result are below.
> >
> > ga-> sdfopen
> > http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc?mld
> [0:1:0][1750:1:2169][1500:1:2300]
> >
> > Scanning self-describing file:
> > http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc?mld
> [0:1:0][1750:1:2169][1500:1:2300]
> > gaopnc error: nc_open failed to open file
> > http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/2d/rarchv.2009_125_00_2d.nc?mld
> [0:1:0][1750:1:2169][1500:1:2300]
> > read_metadata: gaopnc failed
> > gadsdf: Couldn't ingest SDF metadata.
> > ga->
> > Mark
> >
> >     ----- Original Message -----
> >     *From:* Dan Martin <mailto:Dan_Martin at BUOYWEATHER.COM>
> >     *To:* GRADSUSR at LIST.CINECA.IT <mailto:GRADSUSR at LIST.CINECA.IT>
> >     *Sent:* Thursday, April 30, 2009 7:40 PM
> >     *Subject:* Re: Using GrADS to retrieve HYCOM data
> >
> >     The full HYCOM data is on a curvilinear grid that I haven't been
> >     able to
> >     make work in grads. They set up a linear grid for grads users by
> >     cutting
> >     off pre-gridded section above 48 degrees north.
> >
> >     http://hycom.coaps.fsu.edu/opendap/nph-dods/datasets/hycom/global/GLBa0.08_rect/data/
> >
> >     The update schedule is a bit irregular and the server is not
> alway up,
> >     but nice data when it is there.
> >
> >     If anyone has the curvilinear grid version working in grads,
> any tips
> >     would be nice.
> >
> >     Dan
> >
> >     Mark Hess wrote:
> >     > Has anyone out there used GrADS to retrieve and display data
> >     from the
> >     > HYCOM OPeNDAP near real-time data server
> >     > http://hycom.coaps.fsu.edu/thredds/dodsC/
> glb_nrt_analysis.html?
> >     >
> >     > I am hoping to use GrADS to retrieve mixed layer depth data
> from
> >     this
> >     > server, but not real clear on the http/OPeNDAP string I
> would use to
> >     > download the file (whether it be ASCII or binary).  If you
> have done
> >     > this and could send a sample script or command showing the
> http
> >     > line that would be much appreciated.
> >     >
> >     > Thanks,
> >     >
> >     > Mark
> >     >
> >

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