1. 2. 3. 5. 6. From the table look up, estimate the roughness length that is relevant for the wind profile at the mast location. Hint: Use Fig. 1 to guide you. The friction velocity is a measure of the momentum transport from the free atmosphere to the boundary layer. Assuming that the stability effect is small at 10m, use the table value of ZO to derive the variation of the friction velocity U over the 18 hours in the data file by means of Eq. (1). Make a plot of U* as a function of time (use Excel, Matlab, or another computer program). The logarithmic wind profile with the stability correction is given in Eq. (2). Use the time varying U that you just derived and a constant value of Z0 to derive the diurnal variation of the stability correction parameter W. Use the wind speed measurements at 60m and make a plot of as a function of time. Use the measured wind speed at 10 and 40m to derive the roughness length 20 from the logarithmic wind profile without accounting for the stability correction, Eq. (1). The roughness length characterizes the upwind landscape and is thus constant. Hint: Write the logarithmic wind profile expression for the wind speed at both 10 and 40m and express In (zzo) as In(z)-In(zo); then eliminate (u*k), and solve for the roughness length. Calculate it for every instance in the time series and plot Z0 as a function of time. Make plots of the wind direction at 10m and 100m as a function of time and find the difference. Assume that the energy production of a wind turbine is proportional to the cube of the wind speed. Consider you have a 10m tall wind turbine and calculate the wind speed cubed for that height. Plot the values as a function of time.