packing data in binary format for GrADS

[Dan Leins]

All,

Ok yes, following those conventions definitely had the desired effect!

Thanks for pointing me in the right direction!

Dan


On 12/12/05, Diane Stokes <Diane.Stokes at noaa.gov> wrote:
>
> Hi, Dan.
>
> I didn't go through your msg carefully to catch everything, but for
> starters, it doesn't look like you are following the required format
> described at:
>
>   http://grads.iges.org/grads/gadoc/aboutstationdata.html#station
>
> The station id should be the first word in your header and should be
> written out as type character with length 8.  nlev and nflag should be
> written as integer, not float.
>
>    Diane
>
>
> Dan Leins wrote:
> > List,
> >
> > I'm working on a project that involves parsing through a page of text,
> > stripping out the data I want, and writing it to a binary file.
> > Ultimately I would like to take the data in the binary file and plot it
> > as station data in GrADS, but I've come across a problem when I try to
> > write my data out as binary.
> >
> > I'm decoding RR2 SHEF encoded snowfall data, stripping out the LAT/LON
> > of the station of interest, 6/12/24hr snowfall totals (if available,
> > using -999.0 to fill in missing data), and snow depth (again, -999.0 if
> > missing).
> >
> >
> > .A CLE141 1126 Z DH0000/DVH12/SFV 1.5"LAT=41.86 LON=-80.8  ASHTABULA
> 3S"/
> > .A CLE130 1126 Z DH0000/DVH12/SFV 1.5"LAT=41.58 LON=-81.2  CHARDON"/
> > .A CLE221 1126 Z DH0000/DVH12/SFV 1.4"LAT= 41.16 LON=-81.21  RAVENNA
> 1E"/
> > .A CLE032 1126 Z DH0000/DVH12/SFV 5.0"LAT=41.83 LON=-80.09  CAMBRIDGE
> > SPRINGS"/
> > .A CLE020 1126 Z DH0000/DVH12/SFV 3.2"LAT=41.93 LON=-80.3  FRANKLIN
> CTR"/
> > .A CLE023 1126 Z DH0000/DVH12/SFV 0.8"LAT=41.92 LON=-79.64  CORRY"/
> > .A CLE032 1126 Z DH0230/DVH24/SFV 3.0"LAT=41.81 LON=-80.07  CAMBRIDGE
> > SPGS"/
> > .A CLE020 1126 Z DH0000/DVH6/SFV 16.0"LAT=41.93 LON=-80.3  FRANKLIN
> CTR"/
> > .A CLE141 1126 Z DH0000/SD/ 5.0"LAT=41.86 LON=-80.8  ASHTABULA 3S"/
> > .A CLE130 1126 Z DH0000/SD/ 10.0"LAT=41.58 LON=-81.2  CHARDON"/
> > .A CLE221 1126 Z DH0230/SD/ 6.0"LAT=41.34 LON=-81.2  HIRAM RAPIDS"/
> > .A CLE221 1126 Z DH0000/SD/ 6.0"LAT=41.16 LON=-81.21  RAVENNA 1E"/
> > .A CLE032 1126 Z DH0000/SD/ 15.0"LAT=41.83 LON=-80.09  CAMBRIDGE
> SPRINGS"/
> > .A CLE032 1126 Z DH0230/SD/ 7.0"LAT=41.81 LON=-80.07  CAMBRIDGE SPGS"/
> > .A CLE023 1126 Z DH0000/SD/ 17.0"LAT=41.92 LON=-79.64  CORRY"/
> > .A CLE020 1126 Z DH0000/SD/ 12.0"LAT=41.93 LON=-80.3  FRANKLIN CTR"/
> >
> > Using the logic from an existing script...I start w/
> >
> > #!/usr/local/perl/bin/perl
> > open BINFILE, ">snowfall.bin";
> >
> > open (RR2, "<rr2.txt");
> > while (<RR2>){
> >
> > #6 hr snow depth search
> > if (/DVH6\S{4}\s(\d+.\d+)"LAT=(\d{2}.\d+)\sLON=(-\d{2}.\d+)\s/){
> > $sf_6 = $1;
> > $latitude="$2";
> > $longitude="$3";
> > $sf_12= "-999.0";
> > $sf_24= "-999.0";
> > $sd= "-999.0";
> > print "6hr: $sf_6 12hr: $sf_12 24hr: $sf_24 SD: $sd LAT: $latitude LON:
> > $longitude\n";
> > $nLev=1;
> > $nFlag=1;
> > $timeInc=0.;
> > $buffer = pack 'f f f f f f f f f',  $latitude, $longitude, $timeInc,
> > $nLev, $nFlag, $sf_6, $sf_12, $sf_24, $sd;
> > print BINFILE $buffer;
> > }
> >
> > I do the same thing for the other variables too, 12hr, 24hr, and snow
> > depth.  I didn't bother to include them here, they look the same except
> > for the - 999.0 values which vary.
> >
> > At the end of my script, I end w/
> >
> >
> > $nLev=0;
> > $nFlag=0;
> > $buffer = "pack 'f f f f f', $latitude, $longitude, $timeInc, $nLev,
> > $nFlag";
> > print $buffer;
> >
> > exit;
> >
> > Again, following suit with what I've seen before.  I get a snowfall.bin
> > file w/out a problem, but when I go to run `stnmap -i snowfall.ctl`...I
> > get the following error...
> >
> >   Name of binary data set: snowfall.bin
> >   Number of times in the data set: 1
> >   Number of surface variables: 4
> >   Number of level dependent variables: 0
> >
> > Starting scan of station data binary file.
> > Binary data file open: snowfall.bin
> > Processing time = 1
> >   Invalid station hdr found in station binary file
> >   Possible causes:  Invalid level count in hdr
> >                     Descriptor file mismatch
> >                     File not station data
> >                     Invalid relative time
> >     levs = -998653952  flag = 1069547520  time = 1
> >
> > My snowfall.ctl file is pretty straightforward, I'm pretty confident I
> > don't have any errors in there, just 4 variables (6hr,12hr,24hr,sd) and
> > the DTYPE set to station.  While the error is semi-cryptic, I can infer
> > that something's not right with how the data is being written to the
> > binary file.  Like I said, this is more of a problem of getting data
> > into a "grads-readable" format instead of actually using GrADS, but
> > maybe someone has used station data enough to have come across this
> > error.  Does anyone have any insight as to how I can go about fixing it?
> > Any help would be appreciated!
> >
> > Thanks!
> >
> > Dan Leins
> >
>
> --
> Diane Stokes
> Environmental Modeling Center
> National Weather Service/NOAA
>
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