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 Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated.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.
> Steve, > > I have managed to convert individual NARR-A GEMPAK grid files to grib format > and it loads perfectly in IDV. However, my goal is to convert GEMPAK grids > that have been averaged using GDSTAT and convert those files to gribs. These > averaged files as you know have a date/time range to them indead of a single > data/time period. Here are the two approaches I have used to define the > date/time: > > GDATTIM= 971116/1200F000-060224/1200F000 > > GDATTIM= 971116/1200F000:060224/1200F000 > > > Here is my output from GDINFO showing the times. > > NUM TIME1 TIME2 LEVL1 LEVL2 VCORD PARM > 1 971116/1200F000 060224/1200F000 1000 PRES MAXTMPK > 2 971116/1200F000 060224/1200F000 1000 PRES MINTMPK > 3 971116/1200F000 060224/1200F000 1000 PRES AVETMPK > 4 971116/1200F000 060224/1200F000 1000 PRES SDVTMPK > 5 971116/1200F000 060224/1200F000 1000 PRES CNTTMPK > Parameters requested: GDFILE,LSTALL,OUTPUT,GDATTIM,GLEVEL,GVCORD,GFUNC. > > > Is there another way of listing date/time ranges for GDGRIB? > > > --Chris Warren > > > Christopher Warren > Graduate Research Assistant > Plymouth State University > Plymouth, NH 03264 > Email: cjwarren1@mail.plymouth > > Chris, The PDSVAL parameter can be used to set the parameter name, level, time to be used, however, the time interval for your average if much largetr than an hourly value like P06M for example. The easiest solution to get the parameter to grib would be to use GDDIAG and convert the MAXTMPK for that time interval to the TMXK parameter (as defined in $GEMTBL/grid/wmogrib2.tbl parameter #15) such as: GFUNC = maxtmpk GDATTIM = 971116/1200f000:060224/1200f000 GLEVEL = 1000 GVCORD = pres GRDNAM = tmxk^060224/1200 GRDTYP = s GPACK = none GRDHDR = Then use GDGRIB to convert the TMXK to grib. I don't have a good way to encode the time period of gdtat into the grib without doing some direct bit writing in the PDS block. The above use of the single time in GRDNAM in gddiag gets around having to work with the time ranges. Steve Chiswell Unidata User Support Ticket Details =================== Ticket ID: QEJ-861814 Department: Support GEMPAK Priority: Normal Status: Closed