Roughness rose (2005-03-02)

[Old Forum Archivist]

Anemometer mast ~500m from proposed turbine site which is rural/industrial. Is a single roughness rose based on the anemometer position adequate or is a second one sited at the turbine required ? Problem with the latter is:

'The roughness rose 'Turbine' cannot be calculated because:

the associated map does not contain any roughness information.'

No, the map doesn't but the roughness rose does contain values entered manually.

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Hi Anton,



Roughness roses are site-specific. If you associate a roughness rose with a met. station, then it will affect that site only (and will override any roughness information in the associated map).



If you experiment, you will find that a rose can only be associated with one site: you can't insert one at the project level. (This is different from obstacle groups, which can be located in a site-independent way.)



A turbine site will not be affected by a roughness rose which is a child of an associated met. station. The turbine site will need a rose of its own.



You can enter one manually, or you can ask WAsP to generate a rose from the roughness information in a map. If the map doesn't have any, then you can't, of course. If the map does have some roughness information, then there's no real need to generate a rose, unless you want to add more specific detail about the local site environment.



What WAsP does not do is to take a rose from one site and generate a rose for another site.



HTH.

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Hello everyone,

I understand that the roughness rose (RR) are site specific as explained in your last response to Anton, I was wondering if you can help me to better understand the effect of adding a RR to met mast station in a project. I have added a RR to the met mast station (with some particular rougness details), I used also a map with roughness details as a child of the project. I get a self predicted wind speed at the met mast, and I get a WRG at the met station location, I have been very surprised to see that there is a difference betwee the predicted wind spped (self prediction)at the met station and the wind speed predicted at the single met station WRG. Is that mean that WAsP has used the map roughness details to calculate the wind speed predicted at the met station WRG single point instead of using the Roughness rose I have associated to the met station. could you help me to know if my understanding is right...



thank you very much for your excellent forum.



Sam.

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Dear Samuel



A wind resource grid will not be affected by a roughness rose which is a child of an associated met. station. In your case the resource grid member will use the associated map.



WAsP Team


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