[Wrf-users] RE: Constant landuse in wrf output

[Brent L Shaw]

Thorsten,

 

Since you referred to your output files using "d0*", I am assuming you are running a nested grid configuration.  Is the LU_INDEX in your main, outer grid constant as well?

 

I ask this because we discovered a small problem with the Registry.EM settings when running nests.  We were using a 15/5/1km nest configuration, and discovered that the land use index (LU_INDEX) on the 5 and 1 km nests looked remarkably like 15km grid cells, even though we were specifying "fine_input_stream = 2" for all our nests, which is supposed to cause the terrain, land-use, and other high-res static or masked fields to be read from the wrf_input* files while interpolating the atmospheric fields from the parent grid.  In our case, all of the static fields looked correct except LU_INDEX, which was obviously being interpolated from the parent.  It turns out that the line for "LU_INDEX" in the Registry.EM was needed to have "012" added right after the "i" in the I/O control column so that it would be included when fine_input_stream =2.  Changing the Registry.EM and recompiling fixed the problem.  It was really causing poor forecasts in our fine nests for the near-surface fields, because the LU_INDEX impacts roughness lengths, etc., so on our 1km grid you could see obvious "reflections" of the 15km grid in the 2m temp and moisture, 10m U/V, etc.  

 

Maybe this isn't your problem, but I am sure there are others out there that need to know this.  

 

Best regards,

Brent

 

---------------------

Brent Shaw

Senior Meteorologist

Weather Decision <http://www.wdtinc.com/>  Technologies Inc.

1818 W. Lindsey St. 208D

Norman, OK 73069

Mobile: (405) 397-9950

 

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