[Wrf-users] How wrf processes nests

[Gustafson, William I]

Dave,

The grids all share the same processors and are kept in sync at the end of each coarse-domain timestep. So, the outer nest runs on the processors first, then that nest waits while the finer nest is calculated. Then, the fine nest waits while the coarse nest calculates, and on-and-on it goes. So, within a timestep, each nest is run sequentially. However, if one sees thinks of this in terms of the processor usage, they are simultaneous.

-Bill
___________________________________________________________________

William I. Gustafson Jr., Ph.D.
Scientist
ATMOSPHERIC SCIENCES AND GLOBAL CHANGE DIVISION

Pacific Northwest National Laboratory
P.O. 999, MSIN K9-30
Richland, WA  99352
Tel: 509-372-6110
William.Gustafson at pnnl.gov<mailto:William.Gustafson at pnnl.gov>
http://www.pnnl.gov/atmospheric/staff/staff_info.asp?staff_num=5716
http://www.researcherid.com/rid/A-7732-2008



From: <wrf-users-bounces at ucar.edu<mailto:wrf-users-bounces at ucar.edu>> on behalf of David Smith <dsmith at uvi.edu<mailto:dsmith at uvi.edu>>
Date: Wednesday, June 8, 2016 at 12:55 PM
To: wrf-users <wrf-users at ucar.edu<mailto:wrf-users at ucar.edu>>
Subject: [Wrf-users] How wrf processes nests

Hi,

  I am running wrf using mpirun on a 10 node cluster with 12 processors each – 120 total.  I have two fine nests (0.333 km) within a 1.0 km coarser nest.  I am trying to make a judicious choice for the dimensions of the fine nests, to minimize runtime.  (Making one fine nest would double the area.)  Will wrf run the two fine grids sequentially or simultaneously?  I would think this info would be in the users guide, but I’m not finding it.  Thanks!

Dave Smith

Dr. David J Smith
College of Science and Mathematics
University of the Virgin Islands
St. Thomas,  VI  00802
340 693-1257
dsmith at uvi.edu<mailto:dsmith at uvi.edu>

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