Re: interpolating LIB-files (2005-10-27)

[Old Forum Archivist]

Dear Lars Levermann,



I see that no other user replied to this, so I (the LibInt programmer) add my own thoughts.



Rules for using the lib-interpolator?

-------------------------------------

The Lib Interpolator is not based on physics and there are no formal criteria

for its application. However, I suggest that you consider the following questions:

* Are the data from the reference sites measured with similar equipment?

* Are measurement periods and sample intervals comparable?

* Are the WAsP RIX numbers of the reference sites comparable?

* Are the wind atlases of the reference sites comparable?

* Are other climates parameters, e.g. temperature, humidity, and height above sea level, comparable?

* Finally, are the conditions at the new site expected to be comparable to conditions at the reference sites?

Obviously, it is a good thing if you truly can ask YES to all these questions.

Unfortunately, we have no guidelines as to how much you could violate the ideal conditions.



Do I need to interpolate 3 files or can I use only 2?

-----------------------------------------------------

Using 2 files only is equivalent to interpolation along one leg

of the normal interpolation triangle. Create a dummy wind atlas

for the third corner, choose manual weighting factors and set the

factor for the dummy to zero.



Maximum distance from turbine sites or/and between the met. stations?

---------------------------------------------------------------------

I suppose there is a maximum distance but it is not a universal constant.

The relevant questions to consider is whether the sites relates to the same

regional wind climate and whether the WAsP RIX numbers are comparable.



Use of 3 stations where the site isn't located in the triangle?

--------------------------------------------------------------

I do not recommend excessive extrapolation. Try to interpolate between

the two closest stations only.





Good luck!

Morten

--------