ungrib

Structured YAML to run the WRF preprocessing component ungrib (documentation) is validated by JSON Schema and requires the ungrib: block, described below. If ungrib is to be run via a batch system, the platform: block, described here, is also required.

• This driver receives a cycle argument, which it makes available as a Python datetime object to Jinja2 when realizing its input config. This supports specification of cycle-specific values. For example, the key-value pair

  gfs.t{{ cycle.strftime('%H') }}z.atmanl.nc: /some/path/{{ cycle.strftime('%Y%m%d%H') }}/gfs.t{{ cycle.strftime('%H') }}z.atmanl.nc
  

  would be rendered as

  gfs.t18z.atmanl.nc: /some/path/2024021218/gfs.t18z.atmanl.nc
  

  for cycle 2024-02-12T18.

Here is a prototype UW YAML ungrib: block, explained in detail below:

ungrib:
  execution:
    batchargs:
      cores: 1
      walltime: "00:01:00"
    executable: /path/to/ungrib.exe
  gribfiles:
    interval_hours: 6
    max_leadtime: 24
    offset: 0
    path: /path/to/dir/gfs.t{cycle_hour:02d}z.pgrb2.0p25.f{forecast_hour:03d}
  rundir: /path/to/run/dir
  vtable: /path/to/Vtable.GFS
platform:
  account: me
  scheduler: slurm

UW YAML for the ungrib: Block

execution:

See this page for details.

gribfiles:

Describes the GRIB-formatted files to be processed by ungrib.

interval_hours:

Frequency interval of the given files, in integer hours.

max_leadtime:

The maximum forecast leadtime to process. This may be the same as the forecast length, or a lower leadtime.

offset:

How many hours earlier the external model used for boundary conditions started compared to the desired forecast cycle, in integer hours.

path:

An absolute-path template to the GRIB-formatted files to be processed by ungrib. The Python int variables cycle_hour and forecast_hour will be interpolated into, e.g., /path/to/gfs.t{cycle_hour:02d}z.pgrb2.0p25.f{forecast_hour:03d}. Note that this is a Python string template rather than a Jinja2 template.

rundir:

The path to the run directory.

vtable:

The path to the correct variable table for the file to be processed by ungrib.