WAsP 10.1 Rel. C

Release notes

Changes and new features

Version 10.1.0100

10.1 release C:
An installation problem in release B, related to certain turbine-type file-names not accepted by Asian WIndos versions (Korean and Chinese) has been solved.

Version 10.1 - General release notes

HEADLINES

1. Calculations 5-10 times faster
2. Slight differences in results (corrections, climates and RIX) are possible: all previously calculated results marked 'dirty'
3. Surface land fraction introduced in roughness assessments, to handle coastal areas better
4. Some small changes to the project parameter list
5. Offshore mean stability heat flux is revised
6. Help-system updated regarding roughness assignment
7. Resource grid setups can be cloned by copy and paste
8. Wind atlases can have roughness classes up to 5.0m
9. Upper-air TAB files accepted for wind atlas calculations
10. A special standalone legacy build of WAsP 10.0 can be run safely alongside WAsP 10.1

DETAILS

1. The code for calculating the elevation grid for the flow model, RIX and roughness has been revised and improved. The calculations are now 5-10 times faster than before!
2. The changes to the core - the basic flow model - also mean that results are slightly different, so existing results are automatically marked as due for recalculation. Further, RIX values will deviate slightly as the RIX calculation is slightly changed by its integration with the grid generator, i.e. the algorithm taking translating the height-contour data to the polar-grid used in the orographic part of the WAsP flow model.
3. Site roughness assessments now include a surface-land-fraction (SLF) method for the areas surrounding the site, giving a more realistic representation of roughness and stability in coastal areas. The SLF can be visualised in the reference site window roughness rose view. SLF is calculated in the roughness analysis in parallel with the roughness rose by averaging the land/sea indicator (1/0), i.e. an indicator telling whether a point is on land (indicator=1) or sea (indicator=0), which for the moment is based on the roughness length. The SLF value is used when interpolating between land and sea parameters in the stability model.
4. Parameter list in ‘WAsP wind modelling’ changed slightly. Some parameters have been removed, some added and some default values have changed.
   
   a. A parameter governing the decay in the vertical of stability-induced deviations from the log profile has been introduced (“power law in the decay of stability induced perturbation of wind profile”). The similarity scale height of the boundary layer is calculated for the relevant (sector) land roughness and for sea roughness. These can be modified by altering the parameters “Factor in height of boundary layer over land”, “...over sea” (default value 1.0 for both). The stability corrections are attenuated by a factor exp(-(h/H)p), where h is the height and H the boundary layer scale height, using either the land or sea value depending on the site, or an interpolated value using the surface-land-fraction (see above).These modifications allow some tuning of wind distribution profiles at higher levels above ground.
   
   b.The parameter for the precision of roughness assessments has been made open to user modification again (“Max RMS error in log(roughness) analysis”). This parameter is unchanged compared to earlier versions (default value 0.3). It enters into the least-square fitting of the sector-wise roughness rose to the map-derived roughness areas. The roughness rose fitting proceeds in a series of steps, each adding a new roughness change position until either the rms-error falls below this parameter value or the maximum allowed number of changes is reached (parameter “Max. number of roughness changes/sector”).
5. The default offshore mean-stability heat flux parameter has been updated to be more realistic, giving an overall improvement in combination with the new SLF: now -8 W/m² (previously +15 W/m²). This assures a more realistic prediction of off-shore wind profiles, also when based on observed coastal wind data affected by land conditions.
6. The HELP-system has been updated regarding roughness assignments for very smooth land surfaces. This includes inland lakes: always Z0=0; very smooth, wet-like inland surfaces: no lower than 3mm, especially in case of anemometer heights and turbine hub heights > 80m.
7. Resource grid setups can be inserted by copy and paste
8. Wind atlases can now contain roughness classes with roughness lengths up to 5.0 m
9. Upper-air observed wind climates (TAB file format) are supported again as inputs to wind atlas analysis calculations.
10. WASP 10.0 is available on request as a standalone application, which makes comparison of results easy.