[Wrf-users] tmn_update leads do unrealistic soil temperatures

[Heimo Truhetz]

Dear all,

I was able to fix this issue.

The problem is related to the variable TLAG, which is missing in the
restart files since model version 3.7.

When the model is restarted (as it is frequently done in climate
simulations) TLAG is set to zero because it cannot be found in the
restart file. But TLAG is an essential variable for calculating the soil
temperature of the lowest layer and if it is set to zero the soil
temperature of the lowest layer sharply drops. After a few restarts (I
restart the model every simulated month) the soil temperature of the
lowest layer becomes unrealistically low.

The solution is to correct the Registry file by adding TLAG to the
restart stream.

TLAG can be found in Registry.EM_COMMON and the erroneous line

state    real  TLAG             i&j     misc        1         -    
d=(interp_mask_field:lu_index,iswater)u=(copy_fcnm)     "TLAG"        
"DAILY MEAN SFC TEMPERATURE OF PRIOR DAYS"       "K"

should be changed to

state    real  TLAG             i&j     misc        1         -    
rd=(interp_mask_field:lu_index,iswater)u=(copy_fcnm)     "TLAG"        
"DAILY MEAN SFC TEMPERATURE OF PRIOR DAYS"       "K"

(a "r" needs to be added to the entry "d=(interp..."; it should read
"rd=(interp...")


All model versions from 3.7 onwards are affected.

Cheers,
Heimo



On 08/11/2016 10:59 AM, Heimo Truhetz wrote:
> Dear all,
>
> when I make use of the tmn_update option in the NOAH LSM (WRF-ARW
> v3.7.1), the lowest soil layer becomes unrealistically cold after a
> simulation period of about two and a half months: for instance, the
> lowest soil layer freezes in Northern Africa (Sahara).
>
> Is there somebody else, who has seen this strange behavior?
>
> Does anybody have a clue on this?
>
>
> I use the WRF-ARW v3.7.1 and drive it with ERA-Interim. The model domain
> covers an extended area over Europe.
>
>
> Cheers,
>
> Heimo
>
> _______________________________________________
> Wrf-users mailing list
> Wrf-users at ucar.edu
> http://mailman.ucar.edu/mailman/listinfo/wrf-users

-- 
---------------------------------------------------------
Heimo Truhetz, PhD - Vice Head of ReLoClim
Wegener Center for Climate and Global Change (WEGC),
University of Graz, 
Brandhofgasse 5, A-8010 Graz, Austria
phone: +43-316-380-8442
  fax: +43-316-380-9830
eMail: heimo.truhetz at uni-graz.at
  web: http://www.wegcenter.at
---------------------------------------------------------