RE: Grib File

• To: Nelson Brandon K A1C AFWA/SCSA <brandon.nelson@xxxxxxxxxxx>
• Subject: RE: Grib File
• From: Robb Kambic <rkambic@xxxxxxxxxxxxxxxx>
• Date: Fri, 29 Jul 2005 16:35:50 -0600 (MDT)

On Fri, 29 Jul 2005, Nelson Brandon K A1C AFWA/SCSA wrote:

> Hey me again! Another question...
>
from the IndexFormat.txt file:

3. Grib1 file index

Section 1 same as Grib2

Section 2 Grib Records
one line for each record in the file
blank separated

ProductType Discipline Category Parameter LevelType1 LevelValue1 255
LevelValue2
 ReferenceTime ForecastTime Gdskey BmsOrGdsOffset -l DecScale BmsExists^M

>0 0 -1 11 107 0 255 0 2005-07-07T00:00:00Z 69 3495848078 82 23398 1 false

so:

ProductType =0
Discipline =0
Category =0
Parameter =11
LevelType1 =107
LevelValue1 =0
255  // there is not level2Type in Grib1 as in Grib2
LevelValue2=0
ReferenceTime =2005-07-07T00:00:00Z
ForecastTime =69
Gdskey =3495848078
BmsOrGdsOffset = 82
-l =23398 //this is probably what confused you, it's the endOfRecord offset
DecScale =1
BmsExists =false

the text explanation of the first eight number fields are in the one of
the following files:
Grib1ProductDefinitionSection.java GribPDSLevel.java
Grib1GridDefinitionSection.java, and the afwa.tab

robb...
>
> This is a line from the output of the Grib1Indexer class after being run on
> a grib file.  Could you label each of these fields for me?  I looked in the
> file talking about indexes and it didn't make much sense.
>
> You wrote...
>
> you need to look at the index file, file ending with gbx. there a
> explanation of the fields, etc in the IndexFormat.txt file in the root
> dir of the distribution.   the important fields are: BmsOrGdsOffset
> DecScale BmsExists.  the last 4 fields on the product line ignoring
> the -1 field.
>
> There is no -1 on the end of the file line and if I follow the directions
> you gave me before I would be ignoring the 23398 number.  The get data line
> I think I should be writing is
>
> java -Xmx256m ucar/grib/grib1/Grib1GetData us057g1010t04a000000000 82 1
> false
>
> I guess I am just kind of confused but it would help me A LOT if you could
> label each of the fields... Thanks again Robb!
>
>
>
> -----Original Message-----
> From: Robb Kambic [mailto:rkambic@xxxxxxxxxxxxxxxxxxxxxxxx]
> Sent: Wednesday, July 20, 2005 4:29 PM
> To: Nelson Brandon K A1C AFWA/SCSA
> Cc: decoders; support-thredds
> Subject: RE: Grib File
>
> On Wed, 20 Jul 2005, Nelson Brandon K A1C AFWA/SCSA wrote:
>
> > Robb,
> >
> > The problem is I need to write a program that automates it.  This isn't a
> > one time thing with a single grib file.  This is something we do with 100s
> > of grib files every day!  Thanks again for your time!
>
>
> Brandon,
>
> the grib.jar api is just a level to decode the grib files, nj22 sits ontop
> of it to do the work for specifc parameters based on their parameter
> name/number, level type, and level. the nj22 code is available at:
>
> http://my.unidata.ucar.edu/content/software/netcdf-java/index.html
>
> the files used to handle the grib files is located at:
> src/ucar/nc2/iosp/grib in the distribution. i would download the src for
> 2.2.10 and build it. run the toolUI program settng breakpoints in the src
> to find the routines to perform the functions you are investigating.
>
> robb...
>
>
> >
> > --Brandon
> >
> > -----Original Message-----
> > From: Robb Kambic [mailto:rkambic@xxxxxxxxxxxxxxxxxxxxxxxx]
> > Sent: Wednesday, July 20, 2005 12:27 PM
> > To: Nelson Brandon K A1C AFWA/SCSA
> > Cc: support-thredds; decoders
> > Subject: RE: Grib File
> >
> > On Wed, 20 Jul 2005, Nelson Brandon K A1C AFWA/SCSA wrote:
> >
> > > Thanks again for your work Robb!  Basicly what I am trying to do is pull
> > out
> > > specifc parameters based on their parameter name/number, level type, and
> > > level.
> >
> > Brandon,
> >
> > have you looked at that web start program? it does all the tasks that you
> > mention and it will write out a file with only the desired paramters. i
> > will see if there is some more doc on how to use it.  it's based on the
> > java grib.jar that you been working with.
> >
> > robb...
> >
> >
> >
> >
> > Could you point me in the right direction in your code on how I
> > > might do this?  Things like Grib1LookUp look promising but there isn't
> > > enough documentation (which is ok I know it's a beta ;)) for me to
> > > understand it as I am relatively new to grib files.  Thanks for any
> > further
> > > help!
> > >
> > > V/r
> > > Brandon
> > >
> > > -----Original Message-----
> > > From: Robb Kambic [mailto:rkambic@xxxxxxxxxxxxxxxx]
> > > Sent: Tuesday, July 19, 2005 3:20 PM
> > > To: Nelson Brandon K A1C AFWA/SCSA
> > > Cc: support-thredds; decoders
> > > Subject: RE: Grib File
> > >
> > >
> > > well, it looks like we did double the work. i also created a afwa.tab
> and
> > > added it tothe  distribution. the new distribution is in the ftp
> decoders
> > > directory. let me know if you run into any problems.
> > >
> > > robb...
> > >
> > >
> > >
> > > On Tue, 19 Jul 2005, Nelson Brandon K A1C AFWA/SCSA wrote:
> > >
> > > > I have updated your grib table with all of the ones you stated were
> > > missing.
> > > > Let me know when you put this into the build so I can check it out and
> > see
> > > > if there are anymore unknown parametes.  Also it is not Air Force
> Global
> > > > Weather Center anymore.  We are called Air Force Weather Agency!
> > > >
> > > > Thanks a bunch again Robb!  Really been a help and I appreciate your
> > time!
> > > >
> > > > --Brandon
> > > >
> > > > -----Original Message-----
> > > > From: Robb Kambic [mailto:rkambic@xxxxxxxxxxxxxxxxxxxxxxxx]
> > > > Sent: Monday, July 18, 2005 12:10 PM
> > > > To: Nelson Brandon K A1C AFWA/SCSA
> > > > Cc: support-thredds; decoders
> > > > Subject: RE: Grib File
> > > >
> > > >
> > > > Brandon,
> > > >
> > > > after viewing the data, i discovered many missing parameters. i
> couldn't
> > > > find these on the web, do you know a location for a table?  or do you
> > know
> > > > the name, short desc, long desc, and units for the following parameter
> > > > numbers.
> > > >
> > > > 134-137, 140-143, 145-149, 151, 152 155 157, 161, 163, 165-171,
> 191-194,
> > > > 197, 199, 208, 209, 220-223, 227, 228, 230-239, 241, 246, 248-254
> > > >
> > > > robb...
> > > >
> > > >
> > > >
> > > >
> > > >
> > > > On Mon, 18 Jul 2005, Robb Kambic wrote:
> > > >
> > > > > On Mon, 18 Jul 2005, Nelson Brandon K A1C AFWA/SCSA wrote:
> > > > >
> > > > > > It works!  Thanks so much for your time Robb!  I am going to poke
> > > around
> > > > in
> > > > > > the Java files but could you get me a pointer (excuse the
> > programming
> > > > pun)
> > > > > > in the right direction as how to pull out specific parameters from
> a
> > > > grib
> > > > > > file?  Thanks again!
> > > > >
> > > > >
> > > > > Brandon,
> > > > >
> > > > > you need to look at the index file, file ending with gbx. there a
> > > > > explanation of the fields, etc in the IndexFormat.txt file in the
> root
> > > dir
> > > > > of the distribution.   the important fields are: BmsOrGdsOffset
> > > > > DecScale BmsExists.  the last 4 fields on the product line ignoring
> > the
> > > -1
> > > > > field.  for instance product line:
> > > > >
> > > > > 1 0 -1 11 107 0 255 0 2005-07-07T00:00:00Z 0 3495848078 46890 70206
> 1
> > > > > false
> > > > >
> > > > > then the Grib1GetData will grab the data:
> > > > > java -Xmx256m ucar/grib/grib1/Grib1GetData
> > data/us057g1010t04a000000000
> > > > > 46890 1 false
> > > > >
> > > > > will return the temperature data in K.   the product name is from
> the
> > 11
> > > > > the 4th field from the table gwc_2.tab.
> > > > >
> > > > > that's the hard way to extract the data.
> > > > >
> > > > > we have a webstart program called netcdf tools at:
> > > > >
> > > >
> > >
> >
> http://my.unidata.ucar.edu/content/software/netcdf-java/v2.2/webstart/index.
> > > > html
> > > > >
> > > > > a quick way to view the data would be to click the viewer tab and
> then
> > > > > open the folder tab ( on the right side ) to select the data set to
> > > open.
> > > > > this tools works with netcdf, grib, and other types of data. there's
> > > even
> > > > > grid viewer if you select the grids tab, then open the dataset.
> > there's
> > > a
> > > > > red icon on the right to select. the tools program is a test program
> > we
> > > > > use, it's not really a product.
> > > > >
> > > > > robb...
> > > > >
> > > > > >
> > > > > > -----Original Message-----
> > > > > > From: Robb Kambic [mailto:rkambic@xxxxxxxxxxxxxxxx]
> > > > > > Sent: Friday, July 15, 2005 4:45 PM
> > > > > > To: Nelson Brandon K A1C AFWA/SCSA
> > > > > > Cc: decoders; support-thredds
> > > > > > Subject: RE: Grib File
> > > > > >
> > > > > > Brandon,
> > > > > >
> > > > > > are you sure you got the latest GribJava.tar.gz? the latest is:
> > > > > > 711461 Jul 11 14:12 GribJava.tar.gz
> > > > > >
> > > > > > i ran the following w/o any exceptions thrown.
> > > > > >
> > > > > > % java -Xmx256m ucar/grib/GribChecker data/us057g1010t04a000000000
> > > > > > % java -Xmx256m ucar/grib/grib1/Grib1Dump
> > data/us057g1010t04a000000000
> > > |
> > > > > > more
> > > > > > % java -Xmx256m ucar/grib/grib1/Grib1Indexer
> > > > data/us057g1010t04a000000000
> > > > > > | more
> > > > > >
> > > > > > remember the CLASSPATH must be set to find the grib.jar,
> > jpeg2000.jar,
> > > > and
> > > > > > junit.jar.  if you still get exception let me know.
> > > > > >
> > > > > > robb...
> > > > > >
> > > > > >

==============================================================================
Robb Kambic                                Unidata Program Center
Software Engineer III                      Univ. Corp for Atmospheric Research
rkambic@xxxxxxxxxxxxxxxx                   WWW: http://www.unidata.ucar.edu/
==============================================================================