Unified Post Processor (UPP) | FAQ's

UPP can only output Grib2 format.

No, UPP does not currently support netcdf4.

We are not able to support all platform and compiler combinations out there but will try to help with specific issues when able. We always welcome and are grateful for user contributed configurations.

This error indicates a failure in ncep_post. The errors and output from this executable are redirected to a log file upp.f000.out for each forecast hour. Please look in this file for details on what the actual error/problem is.

This may be a memory issue, try increasing the number of cpu’s or spreading them out across nodes (e.g. increase ptiles).

We also know of one version of MPI (mpich v3.0.4) that does not not work with UPP. A work-around was found by modifying the EMC_post/sorc/ncep_post.fd/WRFPOST.f routine to change all unit 5 references (which is standard I/O) to unit 4 instead.

We have received feedback that some parallel builds do not always increase the performance. UPP was optimized for operational use at NCEP, you may see that there is little increase in performance for serial versus parallel on your platform. We are looking into these parallel performance issues.

It is possible that the field you are trying to request is dependent on the core. Also, certain fields can be dependent on model configuration, such as physics choices. Know your data and what you are expecting from the output. We will continue to try to update the user guide as often as possible to reflect limitations, additions, and changes in output fields.

This warning appears for some platforms/compilers because a call in the nemsio library is never used for referenced for a serial build. This is just a warning and should not hinder a successful build of ncep_post or negatively impact your UPP run.

This error message is display when using more recent versions of the wgrib2 utility on files for forecast zero that contain accumulated or time-averaged fields. This is due to the newer versions of wgrib2 no longer allowing for n parameter to be zero or empty.

Users should consider using a separate control file (e.g. postcntrl_gfs_f00.xml) for forecast hour zero that does not include accumulated or time-averaged fields, since they are zero anyway. Users can also continue to use an older version of wgrib2, with the latest known version not resulting in this error being v2.0.4.

For re-gridding Grib2 unipost output, the wgrib2 utility can be used. Complete documentation on grid specification with examples of re-gridding for all available grid definitions can be found at:


Examples of wgrib2 to interpolate to various common grids as well as an example from operations can be found in the Regridding section of the UPP User's Guide.

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