  We study the statistics of the horizontal component of atmospheric boundary
layer wind speed. Motivated by its non-stationarity, we investigate which
parameters remain constant or can be regarded as being piece-wise constant and
explain how to estimate them. We will verify the picture of natural atmospheric
boundary layer turbulence to be composed of successively occurring close to
ideal turbulence with different parameters. The first focus is put on the
fluctuation of wind speed around its mean behaviour. We describe a method
estimating the proportionality factor between the standard deviation of the
fluctuation and the mean wind speed and analyse its time dependence. The second
focus is put on the wind speed increments. We investigate the increment
distribution and use an algorithm based on superstatistics to quantify the time
dependence of the parameters describing the distribution. Applying the
introduced tools yields a comprehensive description of the wind speed in the
atmospheric boundary layer.
