3. Inputs and Outputs

This section describes the input files used when running the UPP and the resulting output files.

3.1. Input files

The UPP requires the following input files:
  • The model forecast file

  • The itag namelist file

  • The GRIB2 control file

  • Additional data files (e.g. lookup tables, coefficient files for satellites)

3.1.1. Model Forecast

The UPP ingests FV3 write component files in parallel netCDF format.

The table below is a list of the unified model variables available from the FV3 model core. Whether a specific variable is able to be read by UPP relies on dependencies such as physics options and model. This table does not include variables that are diagnosed when running the UPP.

UFS Unified Model Variables

3.1.2. ITAG

The file called itag is a text file that contains the fortran namelist &model_inputs as well as the 2D decomposition specification in &nampgb. It is read in by the upp.x executable from stdin (unit 5) and is generated automatically within the UFS application workflow or stand-alone run script based on user-defined options. It should not be necessary to edit this. For description purposes, the namelists &model_inputs and &nampgb (itag file) contain the following lines for FV3:


  1. fileName: Name of the FV3 (pressure level) output file to be post-processed.

  2. IOFORM: Format of FV3 model output (netcdfpara).

  3. grib: Format of UPP output (grib2)

  4. DateStr: Forecast valid time (not model start time) in YYYY-MM-DD_HH:00:00 format (the forecast time desired to be post-processed).

  5. MODELNAME: Model used (GFS, FV3R - regional FV3 also known as the LAM - Limited Area Model).

  6. fileNameFlux: Name of the FV3 (surface) output file to be post-processed.

  7. fileNameFlat: Name of configuration file (postxconfig-NT.txt)


  1. numx: Number of subdomains in the x-direction used for 2D decomposition.

3.1.3. Control File

The user interacts with the UPP through the control file to define what fields and levels to output. It is composed of a header and a body. The header specifies the output file information. The body includes which fields and levels to process.

A default control file, postxconfig-NT.txt, is provided and read by the UPP. For users wishing to customize the control file to add or remove fields and/or levels, they may do so by modifying the postcntrl.xml and then remaking the text file as described in the later section Creating the Flat Text File.


The control file names postxconfig-NT.txt and postcntrl.xml are generic names and are different depending on the application used. Control files for various operational models are located in the UPP/parm directory. Controlling which variables the UPP outputs

To output a field, the body of the control file needs to contain an entry for the appropriate variable. If an entry for a particular field is not yet available in the control file, it may be added to the control file with the appropriate entries for that field. For variables found on vertical levels (e.g. isobaric or height levels), the desired levels to be output must be listed (see next section: Controlling which levels the UPP outputs). A list of available GRIB2 fields that can be output by UPP can be found in the table GRIB2 Fields Produced by UPP. Please note that some fields are dependent on model, physics, and other fields. Controlling which levels the UPP outputs

The <level> tag in the postcntrl.xml file is used to list the desired levels for output. The following levels are currently available for output:

  • For isobaric output, 46 levels are possible, from 2 to 1000 hPa (2, 5, 7, 10, 20, 30, 50, 70 mb and then every 25 mb from 75 to 1000 mb). The complete list of levels is specified in sorc/ncep_post.fd/CTLBLK.f.

    • Modify specification of variable LSMDEF to change the number of pressure levels: LSMDEF=47

    • Modify specification of SPLDEF array to change the values of pressure levels: (/200.,500.,700.,1000.,2000.,3000.,5000.,7000.,7500.,10000.,12500.,15000.,17500.,20000., …/)

  • For model-level output, all model levels are possible, from the highest to the lowest.

  • When using the Noah LSM, the soil layers are 0-10 cm, 10-40 cm, 40-100 cm, and 100-200 cm.

  • When using the RUC LSM, the soil levels are 0 cm, 1 cm, 4 cm, 10 cm, 30 cm, 60 cm, 100 cm, 160 cm, and 300 cm. (For the old RUC LSM, there are only 6 layers, and if using this, you will need to change NSOIL for “RUC LSM” from 9 to 6 in the sorc/ncep_post.fd/WRFPOST.f routine.)

  • When using Pliem-Xiu LSM, there are two layers: 0-1 cm, 1-100 cm

  • For low, mid, and high cloud layers, the layers are \(\geq\)642 hPa, \(\geq\)350 hPa, and <350 hPa, respectively.

  • For PBL layer averages, the levels correspond to 6 layers with a thickness of 30 hPa each.

  • For flight level, the levels are 30 m, 50 m, 80 m, 100 m, 305 m, 457 m, 610 m, 914 m, 1524 m, 1829 m, 2134 m, 2743 m, 3658 m, 4572 m, 6000 m, 7010 m.

  • For AGL radar reflectivity, the levels are 4000 and 1000 m.

  • For surface or shelter-level output, the <level> is not necessary. Creating the Flat Text File

If the control file requires any modifications, a preprocessing step will be required by the user to convert the modified xml file parm/postcntrl.xml to a flat text file parm/postxconfig-NT.txt. The user will first need to edit the postcntrl.xml file to declare which fields are to be output from the UPP.

In order to ensure that the user-edited xml files are error free, XML stylesheets (parm/EMC_POST_CTRL_Schema.xsd and EMC_POST_Avblflds_Schema.xsd) can be used to validate both the postcntrl.xml and post_avblflds.xml files, respectively. Confirmation of validation will be given (e.g., postcntrl.xml validates) or otherwise return errors if it does not match the schema. This step is optional, but acts as a safeguard to avoid run-time failures with the UPP. To run the validation:

xmllint --noout --schema EMC_POST_CTRL_Schema.xsd postcntrl.xml
xmllint --noout --schema EMC_POST_Avblflds_Schema.xsd post_avblflds.xml

Once the xmls are validated, the user will need to generate the flat file. The below command will run the Perl program parm/PostXMLPreprocessor.pl to generate the post flat file:

/usr/bin/perl PostXMLPreprocessor.pl your_user_defined_xml post_avblflds.xml your_user_defined_flat

where your_user_defined_xml is your modified xml and your_user_defined_flat is the output text file.

3.2. Output Files

Upon a successful run, upp.x will generate GRIB2 output files in the post-processor working directory. These files will include all fields that were requested in the control file.

When running UPP stand-alone, the following GRIB2 output files will be generated:

LAM (Limited Area Model): NATLEV.HHH and PRSLEV.HHH

When executed with the provided run script, UPP provides log files in the post-processor working directory named upp.fHHH.out, where HHH is the forecast hour. These log files may be consulted for further run-time information in the event of an error.