Re: NCEP - parameter table

From: David Brown <dbrown_at_nyahnyahspammersnyahnyah>
Date: Thu Jul 22 2010 - 15:13:51 MDT

Hi Jean,

The fact that this parameter has both a parameter number of 255 and a
table version of 255 means that both are classified as 'missing' by
the writers of the GRIB file. The message from NCL is actually a bit
misleading in this case: it is not really an 'unknown' parameter
number (in the usual sense where a number is encountered for which
there is no entry in the tables). Rather, the number 255 explicitly
means 'missing'. So as far as I know there is no way to 'fix' this. I
am not sure why some NCEP-generated GRIB files contain records like
these or what is the significance of their contents. Perhaps someone
on the list can tell us.
  -dave

On Jul 22, 2010, at 9:32 AM, Jean Peres wrote:

> HI all,
>
> I'm trying to open a grib files, but I'm getting the following
> warning:
> warning:NclGRIB: Unknown grib parameter number detected (255, center
> 7, table version 255 grib record 241), using default variable name
> (VAR_255)
> I know that 255 means "missing" , but I really want to fix it.
> I found in email list this link:
> http://www.ncl.ucar.edu/Document/Manuals/Ref_Manual/NclFormatSupport.shtml#GRIB1-built-in-parameter-tables
> But I didn't understand (English isn't my native language).
> What I understood was that I need to set a variable
> NCL_GRIB_PTABLE_PATH - In my case, something like that;
> NCL_GRIB_PTABLE_PATH="/home/jean/NCL_MASTER"
> and create a ".gtb" file with the follow table:
> US Weather Service - NCEP (Parameter table version 141)
> And I have to include the row with 255 information (missing value).
>
> So my doubt is, where do I put the NCL_GRIB_PTABLE_PATH in my
> script and how can I include the missing information at the table.
>
> I hope my English is clear,
>
> And I'd appreciate any help.
>
> --
> Jean Peres
> Meteorologista
> Laboratório MASTER
>
> _______________________________________________
> ncl-talk mailing list
> List instructions, subscriber options, unsubscribe:
> http://mailman.ucar.edu/mailman/listinfo/ncl-talk

_______________________________________________
ncl-talk mailing list
List instructions, subscriber options, unsubscribe:
http://mailman.ucar.edu/mailman/listinfo/ncl-talk
Received on Thu Jul 22 15:13:59 2010

This archive was generated by hypermail 2.1.8 : Wed Jul 28 2010 - 10:42:06 MDT