Heat flux parameters

[mipa]

Hello

Im looking at a project in Sweden and would like to try to adjusted the heat flux parameters for the site.

Can the sitespecific heatflux parameters (offset, RMS) be calculated from the temperature measurments onsite? How is this done?

I think that the site have more stabile conditions and the standard WAsP parameters (if i understand it right) are for more neatrul conditions (slightly stabile.

[Mkevin]

HI,

heatflux parameters can be maesured. If you have Lidar (probably sodar also) on site you can measure w' and theta'. But I think that best solution would be heigher met mast.

[Mark Kelly]

Two things here:

The current (v10) WAsP climatalogical stability treatment uses two parameters (offset and rms heat flux, either over land or water), but these parameters are not physical---so they do not correspond directly to measured surface fluxes. (For details, see Chapter 8 of the European Wind Atlas.)

There is a new stability and "tall profile" treatment scheduled to be included in version 11, which will allow input of measured heat fluxes (or measured flux statistics).

Thus to answer mipa: if you have already checked everything you can regarding the terrain and roughness maps, it is possible to then empirically adjust H_offset to be more negative in order to represent the more stable (in the mean) conditions. But this would be based on wind measurements at multiple heights (e.g. LIDAR).

{side note @Mkevin: I do not believe that commercial wind LiDAR gives usable theta' (yet)...}

[relbert]

Hi Mark, I'm doing wind energy calculations in Brazil's northeast where there is a more unstable atmospheric condition and I'm concerned about how WAsP treats horizontal extrapolations in complex terrain under unstable conditions. The point is, if wind is forced vertically when passing by a hill under unstable conditions, the flow would be dettached and cause convective turbulence. WAsP probably doesn't consider this kind of dynamics but i would like to know how could I evaluate the discrepancy of the results. Do you know any paper that could have some useful information? Thanks in advance.