[Wrf-users] Setting of RADT with multiple nests

Satyaban Bishoyi Ratna satyaban_2001 at rediffmail.com
Wed Apr 1 01:34:04 MDT 2009

Dear Eric,
With your experimental set up, I will prefare to use
radt = 45, 45, 45 as we use for our cases.

WRF document says 
1. recommend 1 min per km of dx
2. use the same value for all nests

So first, we can satisfy condition 1 for the parent domain and next
to follow condition 2 (i.e.) the same 'radt' valuse of outer domain to be used in all the nest domains.


On Wed, 01 Apr 2009 Eric Altshuler wrote :
>I have asked this question before, but I have never gotten a clear answer. I apologize for asking it again.
>I am running WRF-ARW with 3 domains: a coarse grid at 45km resolution, an intermediate nest at 15km, and an inner nest at 5km. The WRF documentation says two things about RADT:
>1. Set RADT (in minutes) equal to the horizontal resolution (in km), e.g. RADT = 10 for DX = 10000
>2. Set RADT to be the same on all domains
>These rules conflict when nesting is used. Obviously, with a 3:1 nesting ratio, it is impossible to satisfy both rules. My question is, which RADT setting should be used here?
>a) radt = 45, 45, 45
>b) radt = 15, 15, 15
>c) radt = 5, 5, 5
>d) none of the above?
>My intuition is to set radt = 15, 15, 15 but I would appreciate feedback on how users deal with the RADT setting when they run WRF with nesting.
>Thanks in advance for your attention.
>Best regards,
>Eric L. Altshuler
>Assistant Research Scientist
>Center for Ocean-Land-Atmosphere Studies
>4041 Powder Mill Road, Suite 302
>Calverton, MD 20705-3106
>E-mail: ela at cola.iges.org
>Phone: (301) 902-1257
>Fax: (301) 595-9793
>Wrf-users mailing list
>Wrf-users at ucar.edu

Satyaban Bishoyi Ratna
Computational Atmospheric Sciences Team
Scientific & Engineering Computing Group
Centre for Development of Advanced Computing (C-DAC)
Pune University Campus, Ganeshkhind
Pune - 411 007, Maharashtra, India
E-mail: satyabanb at cdac.in
Tel (O): +91-020-2570 4226,  (Cell): +91-094223 56326
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