GrADS Utilities: stnmap

## stnmap

`stnmap [-i fname] [-0]`

`stnmap` is an external GrADS utility that writes out a hash table and/or link list information for station data that allows GrADS to access the data more efficiently. After a station data set has been written and the accompanying data descriptor file has been created, you must run the `stnmap` utility before you can look at the data in GrADS.

The `stnmap` options are as follows:

`fname`

The name of the station data descriptor file. If not specified, `stnmap` will prompt the user.

`-0`

Allows processing of certain templated station data sets without actually reading the data.

The output from `stnmap` goes into a file that is named in the `STNMAP` record of the data descriptor file. (See Usage Note #2).

Usage Notes

1. If you change the data file (perhaps by appending another time group), you will also have to change the descriptor file to reflect the changes and then rerun the `stnmap` utility.

2. Note the difference between required records in a station descriptor file and a grid descriptor file:

   `DTYPE`

   specifies a data type of: station
   `STNMAP`
   gives the file name of the station mapping file
   `XDEF, YDEF, ZDEF`
   these records are not specified in a station data control file
   `TDEF`
   describes the time grouping interval and the number of the time groups in the file
   `VARS`
   surface variables are listed first, and show a "0" for the number-of-levels field. Level-dependent variables are listed after the surface variables, and show a "1" in the number-of-levels field.

Examples

Here's a sample descriptor file `stat.ctl` for station data set `ua.reps`:

`DSET ^ua.reps
DTYPE station
STNMAP ^ua.map
UNDEF -999.0
TITLE Real Time Upper air obs
TDEF 10 linear 12z18jan1992 12hr
VARS 8
slp 0 99 SLP
ts 0 99 Temps
us 0 99 U Winds
vs 0 99 V Winds
z 1 99 Heightsa
t 1 99 Temps
u 1 99 U Winds
v 1 99 V WInds
ENDVARS
`

Run the `stnmap` utility:

`stnmap -i stat.ctl`

The station map file `ua.map` is a binary file, which includes the hash table and/or link list information.