NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
Current content can be found at unidata.ucar.edu.
To learn about what's going on, see About the Archive Site.
Greg, The ECMWF sample GRIB data you sent me has some GRIBS using second order packing. Not all use second order packing, so you may see some grids where they don't appear as a constant value. The constant value grids are a result of GEMPAK not providing support for second order packing at this point. I added support to $GEMPAK/source/gemlib/gb/gbgsec.c to decode second order packing as defined in the WMO GRIB documentation, however, ECMWF is apparently adding their own modifications to the standard since they appear to be using ROW-BY-ROW packing accoring to the bit flags, but the bit widths do not agree, nor do the sizes of expected regions. If you have a contact at ECMWF, I can try to implement the ECMWF modifications if I can get documentation on them. I have searched the WEB for the past 3 days, but can't seem to find any code or documentation that is matching the data values I am unpacking. I tried the generic grib/gbytes routines at NCEP and NCAR, but they do the same thing I am doing. The WMO grib documentation lists several bits as reserved. ECMWF appears to be using some of these as well. Steve Chiswell Unidata User Support