WASP table

WASP is a PC-program for the vertical and horizontal extrapolation of wind climate statistics. Waveclimate is able to export WASP files in two formats: the TAB format and the LIB format. Files in TAB or LIB format can be directly imported in the WASP package for further analysis.

A WASP table in TAB format shows the relative joint occurrence of wind speed in rows versus wind direction in columns. The most important differences between a standard 2D scatter table and a scatter table in WASP TAB format are:

A WASP TAB scatter table always shows relative occurrences (per mills) while a standard table shows absolute or relative occurrences (percentages) according to the user preferences.
Occurrences in a WASP TAB table are normalized per directional sector, i.e. the sum of the relative occurrences per sector is always 1000.
Column labels in a WASP TAB table show total relative occurrences per sector (percentages).

A WASP table in LIB format shows per directional sector (first OMNI, then north, northwest etcetera):

The relative occurrence of wind speed (percentage)
The scale parameter of the Weibull curve fitted to the wind speed distribution (m/s or knots)
The shape parameter of the Weibull curve fitted to the wind speed distribution (-)

The number of directional sectors can be adjusted through the user preferences. Note that the unit of the scale parameter can be m/s or knots according to the user preferences. The two-parameter (scale and shape) Weibull distribution used for a WASP LIB table is a special case of the three-parameter Weibull distibution used in extreme value analysis of waveclimate.com. In extreme value analysis, the third Weibull parameter is taken to be the threshold applied to the data prior to estimation of the shape and scale parameters. By setting the threshold equal to zero (and thus using all available wind speed samples for the fit), the three-parameter Weibull fit reduces to the two-parameter Weibull fit applied for WASP LIB tables. At least 100 samples are needed for a Weibull fit. The Weibull parameters are set to dummy (-1) in case too few samples are found in a particular sector or in case the curve fitting procedure failed to produce parameters within a reasonable range (shape parameter is expected to fall inside the range 1-8 and the scale parameter must be positive).