Wind speed overestimation for domain over Canary Islands

Questions and other topics related to UEMS 15.
j0nes2k
Posts: 53
Joined: Wed Feb 03, 2010 5:06 pm

Re: Wind speed overestimation for domain over Canary Islands

Post by j0nes2k » Mon Nov 07, 2016 9:56 am

Hello,

I am just getting back to this topic as I want to improve the forecast quality for my domain. As meteoadriatic pointed out, the domain is probably too small in general.

What is the limiting factor in this case - is the covered geographical area too small? Or is the number of points in this domain too small (138x64 points)?

To put it in other words: if I double the resolution to 2km and thus having 276x128 points, will this have an impact on this problem? Or is it still limited due to its geographical coverage?

Thanks again for your help!

Jonas

meteoadriatic
Posts: 1560
Joined: Wed Aug 19, 2009 10:05 am

Re: Wind speed overestimation for domain over Canary Islands

Post by meteoadriatic » Mon Nov 07, 2016 10:02 am

Hi

Yes number of points is more of problem than area.

Not directly from EMS, but WRF-ARW "best practices" guides are still completely relevant in general:

http://www2.mmm.ucar.edu/wrf/users/name ... c_wps.html
http://www2.mmm.ucar.edu/wrf/users/name ... c_wrf.html

So from WPS link, you can find:
It is recommended to have domains no smaller than about 100x100. Note that there will be about 10 grid points (minimum of 5) on each side, in the boundary zone. If domains are too small, the solution will be determined by forcing data.
You can also read the rest of those two links, you can find very valuable stuff in there...


P.S. If you don't use nesting and improve grid distance to 2km, using NCEP 0.25° data as input, you will still have huge boudary problems I guess... you need nesting in that case without doubt.

j0nes2k
Posts: 53
Joined: Wed Feb 03, 2010 5:06 pm

Re: Wind speed overestimation for domain over Canary Islands

Post by j0nes2k » Thu Dec 01, 2016 9:42 am

Just a short update on this case. I increased the domain size, and I could finally solve this problem. In a slightly larger domain with 158 x 120 points with 4km resolution the error still persisted. After changing the domain resolution to 5km due to timings for my real-time forecasts (with the same number of points) the error seems to be gone.

Thanks everyone and especially @meteoadriatic for your help!

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