[Wrf-users] ref_x and ref_y in geogrid

[Eric Altshuler]

Hello David, 


In the WPS code, all namelist variables are initialized to default values before the namelist is read in. If a namelist variable is not assigned a value in namelist.wps, it will retain its default value. In some cases, the default value is "crazy" (e.g. larger than any conceivable valid value for that variable, as is the case with ref_x and ref_y). There's no need for you to specify these variables unless your reference point is not at the center of your coarse domain. 


Best regards, 


Eric L. Altshuler 
Research Scientist 
Center for Ocean-Land-Atmosphere Studies 
253 Research Hall, Mail Stop 6C5 
George Mason University 
4400 University Drive 
Fairfax, VA 22030 USA 

E-mail: ela at cola.iges.org 
Phone: (703) 993-5725 
Fax: (703) 993-5770 

----- Original Message -----
From: "David Smith" <dsmith at uvi.edu> 
To: "wrf-user-list" <wrf-users at ucar.edu> 
Sent: Thursday, August 15, 2013 3:21:53 PM 
Subject: [Wrf-users] ref_x and ref_y in geogrid 


Hi, 

In geogrid, when I leave ref_x and ref_y as default, the geogrid.log shows astronomically large numbers, 

REF_X = 100000002004087734272.000000 
REF_Y = 100000002004087734272.000000 

so I have set them to the correct values (20 and 23 respectively). It seems to make no difference in the successful execution of geogrid, but why are the default values ( E_WE /2 and E_ SN /2 ) rid i culously wrong numbers? Does this indicate I have something disturbingly wrong somewhere or is this just an artifact? I've posted the namelist.wps below. Thanks! 

&share 
wrf_core = 'ARW', 
max_dom = 3, 
start_date = '2013-08-12_00:00:00','2013-08-12_00:00:00','2013-08-12_00:00:00' 
end_date = '2013-08-12_18:24:00','2013-08-12_18:24:00','2013-08-12_18:24:00' 
interval_seconds = 10800 
io_form_geogrid = 2, 
/ 

&geogrid 
parent_id = 1, 1, 2, 2 
parent_grid_ratio = 1, 3, 3, 3 
i_parent_start = 1, 10, 10, 3 
j_parent_start = 1, 10, 10, 21 
e_we = 40, 61, 118, 88 
e_sn = 46, 76, 163, 56 
geog_data_res = 'modis_30s+10m','modis_30s+2m','modis_30s+30s','30s' 
dx = 9000, 
dy = 9000, 
map_proj = 'lambert', 
ref_lat = 18.08, 
ref_lon = -64.635, 
truelat1 = 16.0, 
truelat2 = 20.0, 
stand_lon = -65.0 
geog_data_path = 'geog' 
/ 

&ungrib 
out_format = 'WPS', 
prefix = 'FILE', 
/ 

&metgrid 
fg_name = 'FILE' 
io_form_metgrid = 2, 
/ 




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