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Subject: Degrib 1.30
Date: Mon, 20 Oct 2003 14:12:30 -0400
From: Arthur Taylor


You all have the unique distinction of being registered on my degrib (aka
NDFD_GRIB2Decoder) mailing list (all 207 of us) (I'd like to welcome:
craigb, jjd1571, jloomis, sdw, jlittle, s_umesh, Jim, dave, Mark Moede,
dmurray, bberoukhim, rscoatesjr, driskellb, Seth Sarakaitis, dpsumption,
Zedong Zhang, Peter Staples, James Scarlett, Mike Coyne, sean, CWaite57,
Janjaap Brinkman, Valerie Mills, thealy, Matthew Deitemeyer, William Brooks,
weatherspier, g.mccarroll, sabatzli, msplitt, GRiley, info, s.rey, Richard
Townsend, Scott Handel, jbrodie, WeatherAVD, luoma, alvaroqx, Betsy Gardner,
Clive Reece, Javier Martinez)

Please let me know (email me) if you want to unregister.
The latest version of the program is on:

----------- General News.
1) As some of you may know, the "powers that be" decided to keep the NDFD
Grids "experimental" as of Oct 1, 2003 (which is why I took my time about
getting out version 1.30). They plan to:
A) "Continue to issue at least some NDFD grids experimentally past Sep 30."
B) "Experimental grids will be transitioned to 'official' over the next 6-12
months once determined ready per the criteria now being reviewed by the

2) NWS focus articles:
A) 9/15/2003:
The "NDFD Technical Workshop Presentations are Available Online". (go to: "")

B) 9/22/2003:
The editor of NWS focus was interested in any NDFD Customers...
Well, since you all use it, any of you want to share what you do with it?
If so, email I'm also curious, so if you feel
comfortable, could you CC me?

C) 10/6/2003:
In the section under "NWS Begins IFPS Era; ..." They mention that the
public comment period on NDFD will be extended through "Dec. 1, 2003". Just
thought I would remind you.

----------- News about this release:
I have just finished putting together version "1.30" (last one that I
announced was "1.27" on 9/9/2003).

This release is mainly focused on:
1) The Big Polygon,
2) Doing coverage grids using Nearest point Interpolation,
3) "-P -cells all" option,
4) Being able to handle operational / experimental URLs.

1) The Big Polygon: I had been generating shape files that were either
point or polygon. The polygons were "small" in that they were the size of a
grid cell. Several people have asked if I could merge polygons that have
the same value, together to create big polygons. This would create smaller
shape files making them easier to work with (particularly in ArcExplorer),
while preserving the information. The small polygons will still be useful
for merging shape files together, but for simple viewing, the big polygons
are much faster. I'm not sure which is preferable from the ArcIMS
perspective. (option is "-C -Shp -poly big" versus "-C -Shp -poly small")

2) Some people have commented that they like the coverage grid option
(-Interp), but found that for discrete variables (weather), they couldn't
use it because it always performed "bi-linear" interpolation, which resulted
in "in-between" values. I have now introduced "-Interp near" and "-Interp
bilinear". As I said, the "near" option should work regardless of the type
of variable, while the "bilinear" option is limited to continuous variables.

3) Some people have asked for a ways to map grid cells to lat/lon so they
can just read the .flt files, and not have to concern themselves with map
projections or ESRI file formats. I have now implemented a "-P -cells all"
option, which should probe all the cells in the GRIB2 file in a similar way
to "-P -pnt <lat>,<lon> -pntStyle 1" method, except at all the cells. For
locations it outputs: <cell x>,<cell y>,<lat>,<lon>.

4) Variables are now considered "Experimental", "Operational", and "Not
Available" (instead of "Available" or "Not Available"). In the ndfd.ini
configuration file, there are now two URL location variables (OperDir and
ExprDir) and two FTP location variables (OperDir and ExprDir). If looks for
"Operational" variables in the OperDir locations, and "Experimental"
variables in the ExprDir locations. That should allow it to handle the
eventual "Operational" status of NDFD variables.

5) James Scott has kindly provided a makefile that works in Mac OS X. The
program now works on : MS-Windows, HP, Linux, IBM-Aix, Mac OS X, and someone
had it working on a Sun. Anyone try it on a palm pilot yet? :-)


As always, I tested this release on my PC (XP), 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). For those with access to
MDL's GDP or NHDW machines, see: /home/taylor/ (./degrib/bin/degrib.lin for
linux or ./degrib/bin/degrib.hp for Hp's)

Please let me know if you have problems.


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