19990727: Using NAGRIB to convert GRIB file to GEMPAK file

Li-Chuan,

I'm glad you were able to decode the data with dcgrib.

I'm still not sure why NAGRIB didn't work for you.
We know that NAGRIB is able to read the data, since GDOUTF=list is
showing you the data products. The problem seems to be that the
appropriate projection for grid #105 is not being found in the 
table. Or else, its possible that your 5.2 and 5.4 distributions 
have gotten confused.

If you still want to check out NAGRIB, I suggest the following:

1) type: echo $GEMTBL
Make sure that the above points to your gempak5.4 tables
directory, eg: $NAWIPS/gempak5.4/tables

If this isn't the case, then its possible that you still have the Gempak 5.2
tables in your path from that source Gemenviron.

2) verify that grid#105 is found in $GEMTBL/grid/grdnav.tbl with:
grep N105 $GEMTBL/grid/grdnav.tbl

this should respond with:
N105 105 STR  90 -105   0  17.529 -129.296  53.771  -22.374  83  83 1.50 0

3) verify that you have bagrib for version 5.4:
GEMPAK-NAGRIB>version

 GEMPAK Version 5.4

That is the only thing I can think of at this time.

Steve Chiswell
Unidata User Support




>From: Li-Chuan Chen <address@hidden>
>Organization: Iowa Institute of Hydraulic Research
>Keywords: 199908031453.IAA00432

>Steve,
>
>       I tried both of the methods you suggested.  The second method works.  I
>got the GEMPAK file out.  Thanks a lot.  But I still have problem using
>the first method.  I removed the old file and set the GDOUTF=list, then
>ran the NAGRIB program.  I attach the output in the following in case
>you still interesting solving the problem:  
>
>
> Changing center table to cntrgrib1.tbl
> Changing vertical coord table to vcrdgrib1.tbl
> Changing WMO parameter table to wmogrib1.tbl
> Changing center parameter table to ncepgrib1.tbl
>
> MESG# NMCGRD# PRM#   VCD#    GEMPAK_TIME       LEVL1 LEVL2  VCRD PARM 
>    1   105    130    102    960717/0000F012        0        NONE
>EMSL        
>    2   105      2    102    960717/0000F012        0        NONE
>PMSL        
>    3   105     39    100    960717/0000F012      100        PRES
>OMEG        
> ...
>       218 GRIB messages were read or scanned from the GRIB file:
>    
>96071700f12_eta.grib                                                   
>
>
>       Thanks again for your help.
>
>
>Li-Chuan Chen
>
>
>
>Unidata Support wrote:
>> 
>> Li-Chuan,
>> 
>> If NAGRIB failed to write the output into a gempak gridded data file,
>> then its possible that you had previously created a gempak file that contain
> ed
>> invalid projection information. If a gempak output file already exists,
>> remove this file and let NAGRIB create the new file.
>> 
>> Try the following:
>> 
>> 1) Try setting GDOUTF=list, then run nagrib to verify what projection
>>    is defined in the gds. I was presuming that since you obtained the data
>>    from COMET, that the NMCGRD# would be 212, such as:
>>  GEMPAK-NAGRIB>gdoutf = list
>>  GEMPAK-NAGRIB>r
>> 
>>  MESG# NMCGRD# PRM#   VCD#    GEMPAK_TIME       LEVL1 LEVL2  VCRD PARM
>>     1   212      7    100    990802/1800F012      975        PRES HGHT
>>     2   212      7    100    990802/1800F012     1000        PRES HGHT
>>     3   212      7    100    990802/1800F012      950        PRES HGHT
>> ...etc.
>> 
>> At this point, as long as the NMC grid number is defined- eg, not #255,
>> you should be able to create the output data file when you set
>> GDOUTF to the disk file you desire.
>> 
>> If you still can't create the output file, please send me the listing
>> of what is included in the grib file.
>> 
>> 2) since you have access to NAWIPS 5.4, you have the program dcgrib.
>> 
>> You can convert the grib data to Gempak format with:
>> 
>> % cat 96071712f12_eta.grib | dcgrib -v -d - 96071712f12_eta.gem
>> 
>> If both of these methods fail, then it would indicate that your $GEMTBL
>> environmantal variable is not correctly pointing to $NAWIPS/gempak5.4/tables
>> or that you do not have read or write permission for either the
>> grib parameter files, or the output file in your work directory.
>> 
>> Steve Chiswell
>>
>