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Fix suspicious GRIB2 table entries #285

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JohnHalleyGotway opened this issue Oct 30, 2024 · 3 comments
Open

Fix suspicious GRIB2 table entries #285

JohnHalleyGotway opened this issue Oct 30, 2024 · 3 comments
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@JohnHalleyGotway
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JohnHalleyGotway commented Oct 30, 2024

While working on issue dtcenter/MET#2780 to incorporate recent updates to GRIB2 tables into the Model Evaluation Tools software for MET version 12.0.0, I ran into the following suspicious entries in the GRIB2 tables. Recommend that you take a look.

  1. NDFD_gribtable.dat has non-unique entries starting on line 27:
{0,1,0,255,8,1,19,215, "TOTALSVRPROB", "Total probability of severe thunderstorms", "??"}, 
{0,1,0,255,8,1,19,215, "TOTALXTRMPROB", "Total probability of extreme severe thunderstorms", "??"}, 

For MET, we've encoded line 28 as 216 instead of 215. However, I'm not positive that that's correct.
2. Line 108 of MRMS_gribtable.dat has the long name and units strings reversed:

{209,10,0,255,161,1,11,1, "MergedReflectivityComposite", "dBZ", "UnQCed Composite Reflectivity Mosaic (max ref)"},

Should be changed to:

{209,10,0,255,161,1,11,1, "MergedReflectivityComposite", "UnQCed Composite Reflectivity Mosaic (max ref)",  "dBZ"},
  1. I also note discrepancies between the content of ncep/gribtable.dat and the GRIB2 documentation.

For example, in this table https://www.nco.ncep.noaa.gov/pmb/docs/grib2/grib2_doc/grib2_table4-2-10-2.shtml, of the entries for XICE (24), YICE (25), FRZMLTPOT (27), MLTDATE (28), and FRZDATE (29) do not appear in ncep/gribtable.dat.

@GwenChen-NOAA notes that Hera:/home/Wesley.Ebisuzaki/grib2/wgrib2/gribtables/ncep/gribtable.dat does contain entries for those. That file contains 1668 lines while ncep/gribtable.dat contains 1569. Recommend reviewing/resolving discrepancies.

@JohnHalleyGotway JohnHalleyGotway changed the title Fix two suspicious GRIB2 table entries Fix suspicious GRIB2 table entries Oct 30, 2024
@edwardhartnett edwardhartnett added the bug Something isn't working label Nov 1, 2024
@webisu
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webisu commented Nov 7, 2024

Can someone provide a link to the official table? I got it off the web back in 11/2015.
I could have made some mistakes or the table was changed.

@JohnHalleyGotway
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Can someone provide a link to the official table? I got it off the web back in 11/2015. I could have made some mistakes or the table was changed.

@webisu, while working on GRIB table updates for the Model Evaluation Tools software (dtcenter/MET#2780), I pulled input from three sources:

  1. The gribtables directory in this NOAA-EMC/wgrib2 repository which is version 3.4.0.
  2. The gribtables directory from wgrib2 version 3.1.4 in hera:/home/Wesley.Ebisuzaki/grib2/wgrib2/gribtables. While the numbering would suggest the 3.4.0 contains all of the 3.1.4 code, I don't think the development was entirely linear.
  3. The NCEP GRIB2 Documentation website.

It isn't entirely clear to me which, if any of these, is the authoritative source for NOAA.
I'll note that ECMWF also provides GRIB2 table definitions (https://codes.ecmwf.int/grib/format/grib2/ctables/).
And other centers, like the USAF, have additional GRIB2 tables that are not included in the NOAA sources.

I wrote up this issue because I ran into a few obvious discrepancies that I wanted to point out. Personally, I'd recommend checking for consistency between the 3 sources listed above. And you might also ask how/when the website docs get updated. Perhaps those really are the authoritative NOAA source?

@webisu
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webisu commented Nov 7, 2024 via email

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