WRF ARW User's Guide - MMM - UCAR

The meanings of the level fields are dependent on the "Level Type" field, and are
summarized in the following table.
Level Level Type From Level1 To Level2
Upper-air 100 * (blank)
Surface 1 0 (blank)
Sea-level 102 0 (blank)
Levels at a specified 105 Height, in meters, of (blank)
height AGL
the level above ground
Fields given as layers 112 Starting level for the
layer
Ending level for
the layer
When layer fields (Level Type 112) are specified, the starting and ending points for the
layer have units that are dependent on the field itself; appropriate values may be found
with the g1print.exe and g2print.exe utility programs.
The second group of fields in a Vtable, those that describe how the data are identified
within the metgrid and real programs, fall under the column headings shown below.
| metgrid | metgrid | metgrid |
| Name | Units | Description |
+----------+---------+-----------------------------------------+
The most important of these three fields is the "metgrid Name" field, which determines
the variable name that will be assigned to a meteorological field when it is written to the
intermediate files by ungrib. This name should also match an entry in the
METGRID.TBL file, so that the metgrid program can determine how the field is to be
horizontally interpolated. The "metgrid Units" and "metgrid Description" fields specify
the units and a short description for the field, respectively; here, it is important to note
that if no description is given for a field, then ungrib will not write that field out to the
intermediate files.
The final group of fields, which provide GRIB2-specific information, are found under the
column headings below.
|GRIB2|GRIB2|GRIB2|GRIB2|
|Discp|Catgy|Param|Level|
+-----------------------+
WPS
The GRIB2 fields are only needed in a Vtable that is to be used for GRIB Edition 2 data
sets, although having these fields in a Vtable does not prevent that Vtable from also being
used for GRIB Edition 1 data. For example, the Vtable.GFS file contains GRIB2 Vtable
fields, but is used for both 1-degree (GRIB1) GFS and 0.5-degree (GRIB2) GFS data
WRF-ARW V3: User’s Guide 3-33