Example for

logarithmic wind profile fitting

logarithmic wind profile fitting

WindDataSuite implements a module for fitting measured wind speed data to logarithmic wind speed profiles in analogy to the atmospheric boundary layer theory.

The fitting can be calculated for the 2-parameter model (friction
velocity u_{*}, roughness length z_{0}) and for the
3-parameter model (friction velocity u_{*}, roughness length z_{0},
displacement height D).

Besides the classical method using linear regression, the logarithmic wind speed profile can also be calculated by using an 1-dimensional flow model. The linear regression is a pure mathematical fitting, whereas the 1-dimensional flow model will use all available relevant measured data in order to determine the actual physical processes within the air column.

In the following example, the height profiles of the measured
wind speeds (black curves) have been fitted to the logarithmic
wind speed profile (3-parameter model, red curves).
The results from the linear regression are depicted in **Fig.1** and **Fig.2**,
the results from the 1-dimensional flow model in **Fig.3** and **Fig.4**,
at two consecutive time steps, respectively.

Fig.1:

Logarithmic wind profile fit, 3-parameter model, linear regression,
t = t_{1}

Fig.2:

Logarithmic wind profile fit, 3-parameter model, linear regression,
t = t_{1} + Δt

Fig.3:

Logarithmic wind profile fit, 3-parameter model, 1D flow model,
t = t_{1}

Fig.4:

Logarithmic wind profile fit, 3-parameter model, 1D flow model,
t = t_{1} + Δt

1 year (365 days), sampling rate 10 minutes

31 height levels of wind speed

31 height levels of vertical wind velocity

31 height levels of wind direction

31 height levels of vertical wind velocity

31 height levels of wind direction

approx. 10 seconds

approx. 1 minute