Dubious Sahara Desert Lakes

Questions related to the use of new landuse, or geographical static data, or to modifications to the existing data
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davidsuculum
Posts: 8
Joined: Mon May 04, 2020 1:26 pm

Dubious Sahara Desert Lakes

Post by davidsuculum » Mon Jul 13, 2020 4:15 pm

Hello,

In the geogrid of the WRF 4.1.4, when selecting "modis_landuse_20class_30s_with_lakes" we have observed lots of lakes in the surroundings of the Sahara desert, which we consider dubious. We attach an image and the namelist.wps. Please, note that we used a static dataset that had 3-4 months at the moment of writing this.

In an older WRF version (WRF 3.6) we used static data that didn't have those lakes.

Thanks.
Attachments
dubious_lakes.png
dubious_lakes.png (7.85 KiB) Viewed 512 times
namelist_wps.txt
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Ming Chen
Posts: 1456
Joined: Mon Apr 23, 2018 9:42 pm

Re: Dubious Sahara Desert Lakes

Post by Ming Chen » Wed Jul 15, 2020 4:00 am

We are aware of the noisy structure of landuse type in MODIS-30s data. Please use the MODIS_15s static input data.
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davidsuculum
Posts: 8
Joined: Mon May 04, 2020 1:26 pm

Re: Dubious Sahara Desert Lakes

Post by davidsuculum » Thu Aug 13, 2020 10:32 am

Hello. Thank you. I executed again the geogrid for WRF 4.1.4 (the version I am using) with the static data of WRF 4.2 (unfortunately, I no longer have the original static data of WRF 4.1.4). I used for MODIS the 15s but I am afraid that the problem, at least in our area, near the Sahara desert, remains.

PMcP80
Posts: 12
Joined: Sat Aug 22, 2020 5:33 pm

Re: Dubious Sahara Desert Lakes

Post by PMcP80 » Mon Aug 31, 2020 8:34 am

Wouldn't these "lakes" be created because some of the zones are below sea level and automatically "filled" by the software?

Ming Chen
Posts: 1456
Joined: Mon Apr 23, 2018 9:42 pm

Re: Dubious Sahara Desert Lakes

Post by Ming Chen » Mon Aug 31, 2020 8:16 pm

I am able to repeat this case and get the same results. I am not sure whether these lakes in the desert truly exist, or they are caused by errors in the dataset. I talked to our expert who knows well the land module, but he also has no idea of lakes in Sahara. I am sorry that I cannot help in this issue.
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