Thompson Scheme (posted 12/13/10)
Problem: WRF Versions 3.2 and 3.2.1 contain a MAJOR bug in the Thompson et al
microphysics option number 8. The bug applies for ALL simulations using this option but is worst for high resolution convective cases because it involves the production of graupel from rain and snow collisions. Any users of this scheme should not trust the results of simulations using these code versions because, instead of creating graupel due to rain/snow collisions, the bug was causing the removal of graupel. This bug is NOT found in earlier versions of WRF.
Besides the bug fix for graupel, other changes have been made to the scheme including a more subtle bug related to rain evaporation that has existed in ALL WRF code versions containing the Thompson et al (2008) scheme since late 2006. This bug was minor in comparison but is fixed in the new code. Any users wishing to fix the rain evaporation bug (involves 2 lines of code) in previous WRF versions may contact the author for details to include this change only.
Also, the intended bug fix replacement file contains a new method to determine the graupel Y-intercept parameter as a design change as well as changes to handle mass/number imbalance checks, especially related to sedimentation. The latter changes are better mathematically and should be hardly visible in real simulations, but came about due to testing the sedimentation scheme in isolation from the rest of the code. The bug-fix code should also be released as part of the next standard WRF code release, though further changes are possible between now and Spring 2011.
Solution: Download a new copy of module_mp_thompson.F.fixed and replace the one in phys/ directory. Recompile.
Restart Issue (posted 4/2/10)
Problem: There are problems with restart produing idential results as continous run for physics options BEP urban option and G3+shallow convection.
Solution: Do not use restart when these options are used.
OpenMP And MPI For Some Physics in V3.2 (posted 4/2/10)
Problem: Certain physics options do not work correctly with OpenMP or MPI compile. These are
- mp_physics = 9 (Milbrandt-Yau scheme) (OpenMP)
- sf_urban_physics = 2 (BEM) (OpenMP)
There is no known problem with these physics options if OpenMP or MPI is not used.
Solution: Do not attempt to use the above listed options with OpenMP or MPI compile.
