[wrfems] temperatures crashing during night over water

Robert Rozumalski rozumal at ucar.edu
Thu Oct 27 11:24:23 MDT 2011

Kurt and Bryan,

No action taken other than my spending 2 days debugging the code looking 
for the source of the
problem in vain.

I'll continue to look for the next release or maybe it will hopefully 
resolve itself when I do the testing.


On 10/27/2011 11:13 AM, Kurt Mayer wrote:
> Bob sent out an email about this back in May... don't know if any 
> action has taken place since then.
> I appreciate the users who brought this problem to my attention.
> There appears to be a bug in the latest version of the WRF EMS (the 
> WRF itself actually)
> in that using the default setting for SST_SKIN (ON) in 
> run_physics.conf will result in excessive
> decreases in the skin temperature over water.
> Change SST_SKIN = 0 (OFF) in your wrfems/conf/ems_run/run_physic
> s.conf(.nmm)
> and wrfems/runs/<domain>/conf/ems_run/run_physics.conf files - ASAP
> A test simulation over the Gulf of Mexico showed water temperatures 
> decreasing from 80F (28C)
> to less than 50F (10C) within a few hours after nightfall.  Setting 
> SST_SKIN = 0 corrected this
> problem.
> Bob
> On Thu, Oct 27, 2011 at 12:05 PM, Bryan Mroczka 
> <Bryan.Mroczka at noaa.gov <mailto:Bryan.Mroczka at noaa.gov>> wrote:
>     I have been playing around with the EMS3.2beta release and have
>     had some issues with my overnight 2meter temperatures over
>     water/ocean. As soon as the model thinks the sun has set, it
>     begins a rapid downward trend in the temps over the water. This
>     eventually leads in a short time to some very unrealistic values.
>     The issue seems to be related to the SST_SKIN variable. The
>     default in the run_physics.conf file states that this should be
>     set to 1. However, when I reset this variable to 0, the issue of
>     low level temps over water goes away. I have tried several
>     different short/long radiation options, always with basically the
>     same result.
>     Can anyone think of why this may be occurring with the SST_SKIN=1
>     variable set. I have attached my run_physics.conf file in hopes
>     that someone might see a conflict in my configuration.
>     Thanks
>     Bryan
>     WFO Tallahassee, FL
>     -- 
>     _Bryan Mroczka_
>     bryan.mroczka at noaa.gov <mailto:bryan.mroczka at noaa.gov>
>     Meteorologist
>     National Weather Service - Tallahassee, FL
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>     wrfems at comet.ucar.edu <mailto:wrfems at comet.ucar.edu>
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> wrfems at comet.ucar.edu

Robert A. Rozumalski, PhD
NWS National SOO Science and Training Resource Coordinator

COMET/UCAR PO Box 3000   Phone:  303.497.8356
Boulder, CO 80307-3000

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