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Problems with LU_INDEX variable in nested domain

srinaldi

New member
Hello,
I want to perform a real case simulation in which I have one nested domain. The namelist.wps and the GEOGRID.TBL I used are in the zip folder attached here (GEOGRID.TBL is the default one). Geogrid program successfully completes and parent domain looks fine, but when I check the geo_em_d02.nc file I see that the child domain shows some problems with the LU_INDEX variable. I included both .nc files in the zip folder. I don't know how to explain to you why the variable looks weird so I attached the .nc file so you can see it better.
Do you have any suggestion about why I encounter this problem?
Thank you very much.
 

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Hi,
I believe the issue stems from a combination of the very high resolution of your domain 2, with the nlcd2011 dataset. I'm not sure why that particular dataset can't handle that hight of a resolution, but I tested this with the nlcd2011 data, and then with the nlcd2009 data, and the 2009 data seems much better. Can you try that dataset, instead?

As a side note, we recommend parent_grid_ratio should not be any larger than a 5:1 ratio. If you're wanting to have a domain that is ~110 m (i.e., your d02 resolution), you should add a nest between it and the parent. Otherwise the transition between nests is too clunky and will likely cause problems with your simulation later during the real and/or wrf process. See this page, which provides some best practice recommendations for setting up a reasonable domain.
 
Hi kwerner,
thank you very much for your response. I was using 9:1 ratio for the parent_grid_ratio because I was using the same settings used in the WRF-Fire tutorial and it works fine for them.
I'll take your suggestion to test the 2009 nlcd dataset. Since I don't have this dataset I have to download it first. I found them here, then I guess I have to follow the steps in the user guide (here) to transform in .bil format and create an index file, is it right?

Have a nice day.
Simona
 
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