Nested Runs - Ndown (geogrid.exe)

Setup the Model domains (geogrid.exe): STEP 1.1

Already have geo_em.d01.nc & geo_em.d02.nc for the domains shown below?

YES - then continue to the next step

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1. Ensure you are in the WPS/ directory

2. Edit namelist.wps
    Make the following changes. Pay special attention to the highlighted values.
    Note: For explanation of these variables see Chapter 3 of the User's Guide, or the Best Practices WPS Namelist

max_dom = 2  
parent_id = 1, 1,
parent_grid_ratio = 1, 3,
i_parent_start = 1, 23,
j_parent_start = 1, 46,
e_we = 91, 88,
e_sn = 100, 79,
geog_data_res = 'default', 'default',
dx = 27000,
dy = 27000,
map_proj = 'mercator',
ref_lat = 28.00,
ref_lon = -79.00,
truelat1 = 30.0,
truelat2 = 60.0,
stand_lon = -75.0,
geog_data_path = 'Your WPS_GEOG data location'

Note: Only some variables require settings for domain 2. Grid distance and map projection do NOT have settings for domain 2.

3. Before running geogrid.exe, let's make sure the domain is in the right location.

ncl util/plotgrids.ncl

    
 

4. Now run geogrid.exe to create static data for this domain:
    Note: This will overwrite any geo_em.d01.nc files you may have from previous runs,
    so save your old files somewhere else if you would like to keep them.

./geogrid.exe

Look for "Successful completion of geogrid" at the end of the run, indicating that all when well during the execution. Also peruse the geogrid.log file for more information.

Make sure that the static files have been create:

   geo_em.d01.nc
   geo_em.d02.nc
 

5. Check the contents of these files:

a. Use the ncdump utility:
    ncdump -h geo_em.d01.nc
b. Use the ncview utility.
c. This file can also be view with any of the supported graphical tools.

Now Interpolate our input data onto these domains