How to change land use category for Black Sea ?

Questions related to the use of new landuse, or geographical static data, or to modifications to the existing data
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francescomaicu
Posts: 24
Joined: Wed Nov 25, 2020 11:45 pm

How to change land use category for Black Sea ?

Post by francescomaicu » Wed Apr 21, 2021 9:19 pm

Dear WRF Supporters,
I'm using the static dataset modis_landuse_20class_15s_with_lakes. Unfortunately the Black Sea is considered as a lake, as you can see in the attached image. This causes WRF to use the Lake module if switched on.
My domain and simulations are focused on the Mediterranean area, and I will provide WRF with the SST for the Med, Black Sea and Atlantic Ocean from
a stand alone ocean model, and in future to be coupled with WRF into CIME. I realize that the SST provided over the Black Sea is not used by WRF, because it is considered as a lake. Am I correct?
In my case the optimal solution to solve definitely the issue would be to change the static field from 21 to 17 (only over the Black Sea), so that every time I would run geogrid in that area, the Black Sea will be ocean. Maybe other users not interested in air-sea coupling would complain because they could experience the inverse problem, using the lake model over the Black Sea.
Alternatively to the first hypothesis, assuming that the lake model runs on grid cells where LU_INDEX = 21, how can I change the LU_INDEX in the geo_em.d01.nc file, only over the Black Sea?
Which is your best recommendation?
Thank you very much.
Francesco
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LU_INDEX_in_geo_em.d01.png

kwerner
Posts: 2328
Joined: Wed Feb 14, 2018 9:21 pm

Re: How to change land use category for Black Sea ?

Post by kwerner » Thu Apr 22, 2021 6:28 pm

Hi,
I assume you are actually interested in using the lake option for your other small lakes in your domain? If not, then the simplest solution would be to just use the "modis_15s" (or modis_landuse_20class_15s) setting, instead of "default" (or modis_landuse_20class_15s_with_lakes).

If you want to use the default option and just want to change the lu_index for those points, there are various methods to do this, but one I'm aware of is an NCL program that allows you to modify each particular grid cell in a netcdf file (which is the format of the geo_em* files). You can find a bit of information about that option in this presentation (start around slide 40). The presentation should also point you to NCL resources that may help. If you run into problems, or have questions, we do have an NCL section in this forum where you can post inquiries and someone from that team will be able to assist you.
NCAR/MMM

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