[Wrf-users] Problem with WRF-ARW BMJ scheme after V2.0.3.1?

[Gary Lackmann]

Hello,

With WRF-ARW V2.0.3.1 we had noted consistent behavior of the BMJ CP 
scheme relative to other models (e.g. MM5, workstation Eta) when we 
compared between cases and simulations.  It is a fairly active scheme.  
When we began running WRF V 2.1 and beyond, we noted a very much reduced 
level of BMJ activity.  This was gleaned not just from the "convective" 
precipitation totals, but also from the heating and moisture tendencies. 
There is about an order of magnitude less parameterized precipitation in 
the newer versions, using BMJ.


In contrast, with the KF scheme, the totals are consistent with what we 
saw in the earlier versions of the model, and the totals are much 
greater than those for the BMJ for the cases we've studies.


Recently, working with graduate student Megan Gentry, we ran the 
Hurricane Ivan case using several different permutations of WRF.  I am 
attaching a plot of the convective precipitation (CTOT) and SLP for Ivan 
using V2.0.3.1 as compared to V2.1.2 (which is very similar to all other 
2.1 or later versions we've tried).  Clearly, there is a huge 
difference.  This issue is not only seen with this case- we've run 
convective cases, other hurricanes, mid-latitude cyclones, etc. and the 
story is the same.


For most of the WRF model runs that we've been doing recently, we have 
used the KF CP scheme due to this perceived issue.  But we wonder if 
others have noticed this, are aware of it, have fixed it, etc. Perhaps 
this issue is well-known and will be addressed in the next release?  If 
so, we would like to know before we invest any effort in trying to fix 
it ourselves.  We've investigated so far as to determine that the issues 
probably lies outside of changes to module_cu_bmj.F. 

Thanks for any info you would like to share about this.

Best Wishes,

Gary Lackmann
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