NAM Data

NAM (North American Mesoscale) Model is a model product from NCEP.

Type: GRIB1 / GRIB2 data

Resolution:

Area - approx. 60W–140W ; 20N–60N ; at 12 km
Output frequency 6 hourly
40 pressure levels

Availability:

From NCAR's RDA site: https://rda.ucar.edu/datasets/ds609.0/
Since Jan 1, 2012

Vtable: Vtable.NAM

Peruse the ungrib/Variable_Tables/Vtable.NAM file to see which fields we are going to try to unpack from the GRIB files.

 

Sample data (January 2020)):

These data are GRIB2, with output frequency of 6 hourly.
The data are available for the period January 9 at 12 UTC, through January 11 at 00 UTC, 2020.

Notes on running UNGRIB for this data

1. Download data and place in directory ../DATA/nam, and then unpack the file

   tar xzvf 20200109_nam.tar.gz

2. Examine the GRIB files, e.g.,
   

   ./util/g2print.exe ../DATA/nam/20200109.nam.t12z.awphys00.tm00.grib2

3. ln -sf ungrib/Variable_Tables/Vtable.NAM Vtable


4. ./link_grib.csh ../DATA/nam/202001


5. Edit namelist.wps
   

   start_date = '2020-01-09_12:00:00',
   end_date = '2020-01-11_00:00:00',
   interval_seconds = 21600,
   prefix = 'FILE',
   

6. ./ungrib.exe

   This will create an ungrib.log for your records.



7. Examine the intermediate files, e.g.,
   

   ./util/rd_intermediate.exe FILE:2020-01-09_12
   ncl /util/plotfmt_ncl 'filename="FILE:2020-01-09_12"'