This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.
>From: Lodovica Illari <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200209101900.g8AJ0u111309
>Hi,
>
>I use the ldm to ingest RUC data. I have tried dcgrib to convert it to a
>gempak file but it gives me the following error message:
>
>Sep 10 17:56:24 dcgrib[14772]: Starting Up
>Sep 10 17:56:24 dcgrib[14772]: Invalid center id/grid id
>combination: 7 236/disk20/data/ldm5/gempak/n
>ps/02091015.ruc_gem
>Sep 10 17:56:24 dcgrib[14772]: can't open file
>/disk20/data/ldm5/gempak/nps/02091015.ruc_gem
>Sep 10 17:56:24 dcgrib[14772]: Exiting
>Sep 10 17:56:24 dcgrib[14772]: 1 WMO msgs, 1 GRIBs decoded, 0 written
>
>
>What do I need to do?
>
>Please note that I use gempak 5.4.
>
>Thanks
>
>Lodovica Illari
>
>
Lodovica,
There are several different RUC grid projections in the data stream
(grid 211 is the 80km, grid 236 is the 40km, and in the future at grid 252
is the 20km).
All grids in a single grid file must have the same projection. The
likely cause of the above message is that the file has been created
when an 80km grid was received, and now a grid 236 40km grid is
trying to be written to the same file. You need to have unique
file names for the different projections.
You can do this by making specific pqact.conf entries for each
RUC projection for dcgrib, or I provided a newer program called dcgrib2
that can replace a template "@@@" with the grid number.
For dcgrib2, you could simply send all ruc data to the decoder with an output
file name of YYYYMMDDHH_ruc@@@.gem.
For dcgrib, separating each grid projection by WMO would look like:
^[YZ].Q... KWBG --> YYYYMMDDHH_ruc211.gem
^[YZ].W... KWBG --> YYYYMMDDHH_ruc236.gem
Steve Chiswell