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Degrib (NDFD GRIB2 Decoder) 
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NOAA / NWS's Meteorological Development Laboratory
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Degrib (NDFD GRIB2 Decoder) |
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Subject: Degrib version 1.17
Date: Tue, 03 Jun 2003 09:55:39 -0400 From: "Arthur.Taylor" Organization: DOC/NOAA/NWS - National Weather Service To: Arthur Taylor Hi You all have the unique distinction of being registered on my degrib (aka NDFD_GRIB2Decoder) mailing list (all 61 of us) (I'd like to welcome: herb.philbrick, jdmn5, parksm, jasonv, and Andy Bailey) Please let me know (email me) if you want to unregister. ----------- First I'd like to share some news... Evidently Glen Sampson has asked that some mention of the NDFD GRIB2 Decoder be put into the next article of the NWS focus. This was due to David Runyan, and Dave Brown's visit to the Arizona Division of Emergency Management. David Runyan was evidently impressed by the ease of use, and although Dave Ruth used the term "plug-n-play", I think from what I read of what David Runyan said, he would have agreed to that term. ----------- I just wanted to let you all know that I have just finished putting together version "1.17" (last one that I announced was "1.13" on 5/14/2003). The latest version of the program is on: www.nws.noaa.gov/mdl/NDFD_GRIB2Decoder/ New to release 1.17: 1) Added the ability to download the data from the http site instead of just from the anonymous ftp site. The http data feed should be faster than the anonymous ftp data feed (and they are coming from the same place). 2) Improved Weather handling in general. This involved adding the ugly strings to the probe option (instead of an arbitrary number), and creating what I consider to be a useable weather .dbf file (instead of just a field of numbers and the prayer that people would look in the .txt meta file for what those number meant). I am looking for suggestions to make the .dbf file even more user friendly. 3) Changed orientation of the .shp files so they start in the lower left. This is the way most grids are defined, but for .flt files, ArcGIS apparently requires they start in the upper left. I do not feel that the .shp / .shx / .dbf files should be made difficult for people to use (and compare to say wgrib output) simply because the .flt file is not as flexible. 4) Created a method to handle date-line spanning polygon files. Basically I allow points to be < 180. It is not optimal, but it is better than having a polygon spanning the globe. Optimally I should split the polygons on the dateline. 5) Changed the probe option to be nearest point in addition to bi-linear interpolation. Since I can't tell right now whether data is discrete or continuous, I have made the default probe option be nearest point. 6) Hopefully fixed all inside out polygons. In 1.13 I had fixed them if there were no missing values being imbedded into the ArcGIS files, but I had separate code for when I did want missing values, which had not been fixed. Since "GRIB1" files tend to not have missing values, they were more likely to be inside out than the NDFD GRIB2 files. 7) Found a bug in the GRIB1 decoding of the reference value. The effect was that the field for GRIB1 files they had a constant value subtracted from it. 8) Updated the projection library to the most recent one available from Albion Taylor at : http://www.arl.noaa.gov/ss/models/cmapf.html. The dmapf (or version 2 of cmapf) library now allows arbitrary radius spherical earths, so its no longer restricted to: 6367.47 km. I'd still recommend that radius since that is what is used in most of the GRIB1 grids. 9) Can now probe a "GRIB1" file (in addition to the "GRIB2" file) 10) Made probe pay attention to the -Decimal option (how many decimals to round to.) 11) Improved usage of "GRIB1" with missing, by using 9999 for missing if possible. If not, then defaults to what wgrib used which was 9.999e20. ----------- As always, I tested this release on my PC (win 2000), a Linux machine, a HP-Unix machine, and an AIX-Unix (machine). Although I may have missed something in my testing, it should at least compile, and run for some of the test cases. For those of you with access to the NWS NCEP machine, my current version is in: /nfsuser/g06/we25at/degrib (on snow/frost, I'm no longer using asp/bsp). For those with access to MDL's GDP or NHDW machines, see: ~taylor/degrib/ Please let me know if you have problems. ----------- Regards, Arthur
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