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============================================================================== Robb Kambic Unidata Program Center Software Engineer III Univ. Corp for Atmospheric Research rkambic@xxxxxxxxxxxxxxxx WWW: http://www.unidata.ucar.edu/ ============================================================================== ---------- Forwarded message ---------- Date: Wed, 22 Oct 2003 15:35:19 -0500 From: Tom Whittaker <tomw@xxxxxxxxxxxxx> To: Robb Kambic <rkambic@xxxxxxxxxxxxxxxx> Subject: Re: 20031022:GRIB2 to netCDF Thanks, Robb. I didn't realize the GRIB2 was soooo much better at compressing things that GRIB. While this means the CONDUIT feed might be "right" eventually (where there are decoders in the LDM), the real issue remains that the NWS needs to put the NDFD grids in a NOMADS-serving environment so that the data can be pulled... tom Robb Kambic wrote:
On Wed, 22 Oct 2003, Tom Whittaker wrote:>>>Keywords: 200310221429.h9METkOb014773 Hi Robb... Thanks for your info. Actually, I'm in an email discussion with NWS about NDFD grid distribution and wanted to let them know that GRIB2 is currently an issue for our community. I'm still trying to get them to understand that we don't always want to have to ftp complete files, convert them into NetCDF and put them on our own DODSTom, Here are some rough estimates on the grib2->netCDF file size conversions. A 5.8 meg grib2 ends up as a 180+ meg netCDF file. The grib2 has has multple packing schemes/groups of data inside the file and it can have as many groups it needs to be efficient. Also grib2 has methods to encode missing values w/o using any data space. It's actually efficient in packing the data. Comparing this to grib1->netCDF, it is usually a 10 fold increase, ie grib1 5 meg end up as 50 meg netCDF. Just wanted you to know this as size might be an issue in getting the data on NOAAport, CONDUIT, etc. THREDDS is working on putting a netCDF API on top of grib1 and grib2 files w/o actually converting them to netCDF. This is in very early development stages but it will happen. Robb...servers (or send the original files via the IDD where they can be 'decoded' for use). They still believe that every university has and can use gribtonc and they should, therefore, just FTP the NDFD data. I'm pushing them to use the NOMADS model (the one that uses DODS... ;-) We'll see. Thanks again for the info...sorry I don't have any other examples for ya... tom Robb Kambic wrote:On Wed, 22 Oct 2003, Unidata Support wrote:------- Forwarded MessageTo: Unidata Support <support@xxxxxxxxxxxxxxxx> From: Tom Whittaker <tomw@xxxxxxxxxxxxx> Subject: GRIB2 to netCDF? Organization: UCAR/Unidata Keywords: 200310221429.h9METkOb014773Is there a GRIB2 to NetCDF converter currently available?Tom, Funny you should ask, that's what I've been working on/off for the last couple of months. So far the the only grib2 files that I have to work with are the NDFD files, those you saw displayed at the Usercomm meeting. Do you have any others? would like to test the it on other files. The coding progress is the grib2 files have been decoded, now they Grib2 objects need to be conneected to the java API. I'm estimating a couple weeks to a month depending on the how much time I get to work on it. Robb...Thanks. tom -- Tom Whittaker (tomw@xxxxxxxxxxxxx) University of Wisconsin-Madison Space Science and Engineering Center Cooperative Institute for Meteorological Satellite Studies Phone/VoiceMail: 608.262.2759 ------- End of Forwarded Message============================================================================== Robb Kambic Unidata Program Center Software Engineer III Univ. Corp for Atmospheric Research rkambic@xxxxxxxxxxxxxxxx WWW: http://www.unidata.ucar.edu/ ==============================================================================-- Tom Whittaker (tomw@xxxxxxxxxxxxx) University of Wisconsin-Madison Space Science and Engineering Center Cooperative Institute for Meteorological Satellite Studies Phone/VoiceMail: 608.262.2759============================================================================== Robb Kambic Unidata Program Center Software Engineer III Univ. Corp for Atmospheric Research rkambic@xxxxxxxxxxxxxxxx WWW: http://www.unidata.ucar.edu/ ==============================================================================
-- Tom Whittaker (tomw@xxxxxxxxxxxxx) University of Wisconsin-Madison Space Science and Engineering Center Cooperative Institute for Meteorological Satellite Studies Phone/VoiceMail: 608.262.2759
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