1 arc-second land use nlcd2011_30m 95 vs. 40 categories

Questions related to the use of new landuse, or geographical static data, or to modifications to the existing data
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gjduine
Posts: 4
Joined: Thu Nov 08, 2018 10:43 pm

1 arc-second land use nlcd2011_30m 95 vs. 40 categories

Post by gjduine » Fri Mar 12, 2021 10:29 pm

Hello,

I want to use land cover in WRF at 50 meter is horizontal grid spacing. One thing I found on this forum that there is actually a prepared dataset (http://www2.mmm.ucar.edu/people/duda/fi ... 30m.tar.gz) in this feed viewtopic.php?t=372 I believe it's been created by Michael Duda but I might be wrong.

So this dataset uses NLCD2011 land cover in this classification https://www.mrlc.gov/data/legends/natio ... 011-legend

From the forum post, it is my understanding that this dataset (nlcd2011_30m) should work in WRF directly without having the need to reclassify the native values to values desired by WRF. However, I'm a little confused with the results I obtain after using this data and running geogrid: it's still the native 95 categories, instead of the required 40. For example, ncdump -h would give the following attributes that are critical here I think:

mminlu = NLCD40 ; but
num_land_cat = 95

The land use seems to still follow the classification scheme from native NLCD 2011 (see the legend in the link above). This is different than using the more standard prepared land cover nlcd2006_30s that would give
mminlu = NLCD40
num_land_cat = 40

which matches with the values of LANDUSE.TBL, for example. Also, plotting them would give the native values (ie. range 1-95) for the nlcd2011_30m dataset, and the NLCD40 values (ie. range 1-40) for nlcd2006_30s dataset. How can I tell whether WRF understands this difference and is able to apply the NLCD40 classification system correctly?

I guess one other solution is to create an additional entry in LANDUSE.TBL called "NLCD95" for the native classifications such that it matches the NLCD40 entries.

Any advice on this matter would be great.

Thanks,

Gert-Jan

kwerner
Posts: 2287
Joined: Wed Feb 14, 2018 9:21 pm

Re: 1 arc-second land use nlcd2011_30m 95 vs. 40 categories

Post by kwerner » Thu Mar 18, 2021 7:05 pm

Hi,
Can you attach your namelist.wps file for this? Did you modify your GEOGRID.TBL? If so, will you please attach that, as well? Thanks!
NCAR/MMM

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