GradsDODS
Arlindo da Silva
dasilva at ALUM.MIT.EDU
Fri Feb 8 17:15:48 EST 2008
On Feb 8, 2008 9:47 AM, Steven Weiss <sweiss at iafrica.com> wrote:
> Hi Arlindo,
>
> I downloaded the latest lats4d.gs and am getting errors. See reults below.
>
Hmm. I got this to work:
lats4d -i
http://nomad5.ncep.noaa.gov:9090/dods/waves/nww3/nww320080206/nww3_18z -o
test -lat -35 -30 -lon 17.5 30 -v -format grads_grib -vars htsgwsfc
BTW, I am using
lats4d: Version 1.9.4 of 28 Nov 2007
while you seem to be using a much earlier version:
lats4d: Version 1.7 of 10 May 2006
I am attaching my latest. I'll be posting this on sf.net shortly.
Let me know whether it works.
Arlindo
>
> Regards
> Steven
>
> 1ga-> lats4d -i
> http://nomad5.ncep.noaa.gov:9090/dods/waves/nww3/nww320080206/n3_18z -o
> test -vars htsgwsfs -lat -35 -30 -lon 17.5 30 -v -format grads_grib
> lats4d: Version 1.7 of 10 May 2006
> No hardcopy metafile open
> All files closed; all defined objects released
> All GrADS attributes have been reinitialized
> Scanning self-describing file:
> http://nomad5.ncep.noaa.gov:9090/dods/waves/nww3/nww320080206/nww3_18z
> Found 11 data variables in SDF file.
> Found displayable variable dirpwsfc with 0 levels in SDF file.
> Found displayable variable dirswsfc with 0 levels in SDF file.
> Found displayable variable htsgwsfc with 0 levels in SDF file.
> Found displayable variable perpwsfc with 0 levels in SDF file.
> Found displayable variable perswsfc with 0 levels in SDF file.
> Found displayable variable ugrdsfc with 0 levels in SDF file.
> Found displayable variable vgrdsfc with 0 levels in SDF file.
> Found displayable variable wdirsfc with 0 levels in SDF file.
> Found displayable variable windsfc with 0 levels in SDF file.
> Found displayable variable wvdirsfc with 0 levels in SDF file.
> Found displayable variable wvpersfc with 0 levels in SDF file.
> lats4d: Data file is
> File 1 : WAVE_nww3 Global wave model fcst from 18Z06feb2008, downloaded
> Feb 06 23:11 UTC
> Descriptor:
> http://nomad5.ncep.noaa.gov:9090/dods/waves/nww3/nww320080206/nww3_18z
> Binary:
> http://nomad5.ncep.noaa.gov:9090/dods/waves/nww3/nww320080206/nww3_18z
> Type = Gridded
> Xsize = 288 Ysize = 157 Zsize = 1 Tsize = 61
> Number of Variables = 11
> dirpwsfc 0 -999 ** surface primary wave direction [deg]
> dirswsfc 0 -999 ** surface secondary wave direction [deg]
> htsgwsfc 0 -999 ** surface sig height of wind waves and swell [m]
> perpwsfc 0 -999 ** surface primary wave mean period [s]
> perswsfc 0 -999 ** surface secondary wave mean period [s]
> ugrdsfc 0 -999 ** surface u wind [m/s]
> vgrdsfc 0 -999 ** surface v wind [m/s]
> wdirsfc 0 -999 ** surface wind direction [deg]
> windsfc 0 -999 ** surface wind speed [m/s]
> wvdirsfc 0 -999 ** surface direction of wind waves [deg]
> wvpersfc 0 -999 ** surface mean period of wind waves [s]
>
> lats4d: Dimension environment file same as data file
> lats4d: creating LATS PARAMETER TABLE file .grads.lats.table
> LATS warning (lats_parmtab): Closing the previously opened Parameter
> Table: .grads.lats.table
> lats4d: time range: 18Z06FEB2008 18Z06FEB2008 by 1, delta t: 3 hourly
> lats4d: vertical levels: 0
> lats4d: invalid plev 0 for GRIB output
> lats4d: using HYBRID level number for vertical coordinate
> lats4d: latitudinal range: -35 -30
> lats4d: longitudinal range: 17.5 30
> Failure reading SDF data. #1
> Data Request Error: Error for variable 'dirpwsfc'
> Error ocurred at column 1
> DISPLAY error: Invalid expression
> Expression = dirpwsfc
> lats4d: error creating grads_grib file test.grb
> Original Message -----
>
> *From:* Arlindo da Silva <dasilva at ALUM.MIT.EDU>
> *To:* GRADSUSR at LIST.CINECA.IT
> *Sent:* Friday, February 08, 2008 3:56 PM
> *Subject:* Re: GradsDODS
>
> On Feb 8, 2008 1:44 AM, Steven Weiss <sweiss at iafrica.com> wrote:
>
> > Hi,
> > I am downloading a grib file and processing it through my script. It all
> > works great. I have since discovered that I can avoid the 34mb download by
> > using gradsdods and opening up a server url e.g.
> > http://nomad5.ncep.noaa.gov:9090/dods/waves/nww3/nww320080206/nww3_18z
> >
> > I can run my script over this successfully however it is painfully slow.
> > I am retrieving all the variables over 180hr for a specified lat/lon grid
> > point.
> >
>
>
> Grib2 has great compression capabilities at the expense of speed: it takes
> time to decompress the files. While switching to GRIB2 may have decresead
> data storage requirementments for the data producers and download time for
> the people getting the actual files, it certainly caused a degradation of
> the OPeNDAP services for sites serving the grib-2 files directly.
>
>
> >
> > A little bit of investigation tells me that I should be downloading a
> > subset of the data to my local drive i.e. a lat/lon range and running my
> > script over that instead.
> >
> > How can I do this? Some examples would be useful.
> >
> >
>
> If you want to do this over OPeNDAP you can use lats4d (see recent posting
> for the latest script). Here is an example for creating a subset of the
> data:
>
> lats4d -i
> http://nomad5.ncep.noaa.gov:9090/dods/waves/nww3/nww320080206/nww3_18z -o
> myfile -vars *ugrdsfc *vg*rdsfc -lat 20 60 -lon -100 20 -v*
> **
>
> If you omit -vars, you get all variables, if you omit the -lat/-lon you
> get the whole domain; you can also specify -time/-levs if you would like to
> subset along those dimensions. In grads v1.9, by default this will
> produce a netcdf file called myfile.nc; use "-format grads_grib" to get a
> grib-1 file, "-format stream" to get a flat binary, "-format sequential" for
> a f77 sequential file. At this point you can only specify -format
> sream/sequential with grads v2.
>
> Another point, you can use this command inside gradsdods, or from the unix
> command line with the lats4d sh(1) script (this also be done under windows
> if using sh.exe or tcsh.exe). The command line wrapper is useful for
> putting lats4d based fetches on a crontab.
>
> Arlindo
>
>
>
>
>
>
>
>
>
> > Regards
> > Steven
> >
>
>
>
> --
> Arlindo da Silva
> dasilva at alum.mit.edu
>
>
--
Arlindo da Silva
dasilva at alum.mit.edu
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