[Dart-dev] DART/branches Revision: 11405

dart at ucar.edu dart at ucar.edu
Tue Mar 28 16:09:53 MDT 2017

nancy at ucar.edu
2017-03-28 16:09:53 -0600 (Tue, 28 Mar 2017)
change the default of 'distribute_mean' in the &assim_tools_nml
namelist.  since this item is new with the manhattan release,
people with existing input.nmls may not have this item in their
namelist and so the default value is even more important.  we chose
to have it run faster - if the state vector is large the program
will crash with an out-of-memory error and changing the value of
this item may enable them to run.  the converse setting ran but
could be very slow for some models.

Modified: DART/branches/rma_trunk/assimilation_code/modules/assimilation/assim_tools_mod.f90
--- DART/branches/rma_trunk/assimilation_code/modules/assimilation/assim_tools_mod.f90	2017-03-28 16:44:48 UTC (rev 11404)
+++ DART/branches/rma_trunk/assimilation_code/modules/assimilation/assim_tools_mod.f90	2017-03-28 22:09:53 UTC (rev 11405)
@@ -168,8 +168,13 @@
 ! sections.  to try out the alternatives, set this to .false.
 logical  :: only_area_adapt  = .true.
-! Option to distribute the mean.
-logical  :: distribute_mean  = .true.
+! Option to distribute the mean.  If 'false' each task will have a full
+! copy of the ensemble mean, which speeds models doing vertical conversion.
+! If 'true' the mean will be spread across all tasks which reduces the
+! memory needed per task but requires communication if the mean is used
+! for vertical conversion.  We have changed the default to be .false.
+! compared to previous versions of this namelist item.
+logical  :: distribute_mean  = .false.
 ! Lanai bitwise. This is for unit testing and runs much slower.
 ! Only use for when testing against the non-rma trunk.

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