Re: Reading ECHAM grib files

Hi Marston,
You are correct that the unknown parameter warnings are not that big a deal. Various centers often add new parameters to existing GRIB tables and NCL's built-in tables are not always completely up-to-date. Sometimes the center has not yet given a usable definition. In this case, you have an ECMWF dataset that uses table 128: Parameters 24 and 25 are described as
follows (http://www.ecmwf.int/publications/manuals/d/gribapi/param/filter=grib1/order=paramId/order_type=asc/p=1/table=128/):

Reserved for future unbalanced components ~ ~ 24 grib1 grib2
Reserved for future unbalanced components ~ ~ 25 grib1 grib2

As you can see no short name or units are defined and the "longname" is not something we would want to present to users.

The other message indicates that the latitude coordinates for the Gaussian grid that at least some variables in the file use is wrong or incomplete.
The data itself is presumably correct.

As Dennis suggests, it would be good for us to take a look at this to see what the issue is. So please upload a sample file using his instructions.
What version of NCL are you using? There have been some fixes to the Gaussian coordinate code in recent versions.
  -dave

On May 29, 2013, at 8:02 AM, Dennis Shea <shea@ucar.edu> wrote:

> These are warning messages.
>
> NCL has multiple GRIB tables built into it. This allows
> NCL to assign the appropriate meta data (long_name, units, etc).
>
> NCL unpacks these variables correctly. It just does not
> have the meta data available. You must access
> the appropriate GRIB table.
>
> If you have a sample file and the appropriate GRIB table (or
> point us toward the table), it will be added to the next release
> of NCL.
>
> ftp ftp.cgd.ucar.edu
> anonymous
> email
> cd incoming
> put ....grb
> put table
> quit
>
> On 5/29/13 5:41 AM, Marston Johnston wrote:
>> Hi,
>>
>> I'm trying to extract data from several ECHAM6 grib files using ncl.
>> Already when I try
>> and open the file and read the variable names I get warnings. I don't think
>> the issue with the name is a big deal. Do I need worry about the others? If
>> so I'm unsure how to solve the problems.
>>
>> warning:NclGRIB: Unknown grib parameter number detected (24, center 98,
>> table version 128 grib record 28), using default variable name (VAR_24)
>> warning:NclGRIB: Unknown grib parameter number detected (25, center 98,
>> table version 128 grib record 37), using default variable name (VAR_25)
>>
>> warning:GdsGAGrid: Possible error generating Gaussian latitude coordinates:
>> continuing anyway
>> warning:GdsGAGrid: Gaussian latitude coordinate array is partially or
>> wholly undefined
>>
>> Sincerely,
>> /Marston
>>
>>
>>
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Received on Wed May 29 13:03:08 2013