NARR Data

NARR (North American Regional Reanalysis) data.

Type: GRIB1 data

Resolution:

Area - approx. 160E–20W ; 10N–80N ; at 32 km
Output frequency 3 hourly
30 pressure levels

Availability:

From NCAR's RDA site at: https://rda.ucar.edu/datasets/ds608.0/ (You must register -it is free- to access the data.)
Since Jan 1, 1979
Download the 3D, flx and sfc files for the date of interest.
The downloaded files will have the following file names:

merged_AWIP32.YYYYMMDDHH.3D
merged_AWIP32.YYYYMMDDHH.RS.flx
merged_AWIP32.YYYYMMDDHH.RS.sfc

Also download the FIXED file, called "rr-fixed.grb" (you only need to do this once). This file contains the fields, LANDSEA; SOILHGT; SOIL_CAT and VEGCAT. The date stamp in this file is 1979-11-08_00. See notes below for how to use these different files.

Vtable: Vtable.NARR

Peruse the ungib/Variable_Tables/Vtable.NARR file to see which fields we are going to unpack from the GRIB files. This file also contains notes regarding which fields are obtained from which of the above files.

 

Sample data (January 2020):

The data are available for the period 2020-01-09_12 to 2020-01-11_00 (data frequency is 3 hourly).
This is GRIB 1 data.

Notes on running UNGRIB for this data

1. Download data and place in directory ../DATA/narr


2. Examine the GRIB files, (as an example we will look at a surface file, but also examine the other files)

   ./util/g1print.exe ../DATA/narr/merged_AWIP32.2020010912.RS.sfc



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



4. Now link in the gribbed files. You will have to run ungrib two separate times - once for the fixed input and again for the remaining data.

   ./link_grib.csh ../DATA/NARR/rr-fixed.grb



5. Edit namelist.wps

   start_date = '1979-11-08_00:00:00',
   end_date = '1979-11-08_00:00:00',
   interval_seconds = 10800,
   
   &ungrib
   prefix = 'NARRFIX',

6. ./ungrib.exe


7. Now link in the 3d, sfc, and flx data and run ungrib again.

   ./link_grib.csh ../DATA/NARR/merged_AWIP32.202001

   Note: The above command will link in all the 3D, flx and sfc data files for the time of interest so that we can work with them as a single dataset.


8. Edit namelist.wps

   start_date = '2020-01-09_12:00:00',
   end_date = '2020-01-11_00:00:00',
   interval_seconds = 10800,
   
   &ungrib prefix = 'NARR',

9. ./ungrib.exe


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

    ./util/rd_intermediate.exe NARRFIX:1979-11-08_00
    ncl util/plotfmt_ncl 'filename="NARRFIX:1979-11-08_00"'

You only have to do steps 4a-6a once, even if you change to a different case date, as this is a fixed file. Steps 4b-6b must be repeated for each new case date.

 

Notes on running METGRID for this data

Since we have changed the 'prefix' in the namelist, ensure that you set 'fg_name' correctly before running metgrid.exe:

fg_name = 'NARR'

We also have some constant fields we need to input into the met_em* files. To do this ADD, the following line to the metgrid section of the namelist:

constants_name = './NARRFIX:1979-11-08_00'