Given these wind measurements over a 3 m high sunflower crop: [z (m), M (m s¯¹)] = [5, 4.26], [10, 5.5], [20, 6.61]. Find the displacement distance, d, roughness length, Zo, and friction velocity, u*. Note k=0.4 and is the Von Karman constant. - Z d In M = 11-Ir k Zo you can use the following procedure to find d, Zo, and u⭑: (1) use a spreadsheet to plot your M values on a linear horizontal axis versus In( [z-d]) values on a linear vertical axis; (2) Experiment with different values of d until you find the one that aligns your wind points into a straight line; (fit linear regression line, displaying the equation on the chart, with r² as well, to the three points and find the values of d that give an r² closest to 1. Pick the mid- point). To experiment note that when d=0 the line bends up slightly and when d=4 the line bends down a lot. So d is somewhere between 0 and 4. Find d to 1dp. (3) extrapolate that straight line to M = 0, and note the resulting intercept on the vertical axis, which is equal to In(20) to find the at aligh pomts into a straight line; (fit linear regression line, displaying the equation on the chart, with r² as well, to the three points and find the values of d that give an r² closest to 1. Pick the mid- point). To experiment note that when d=0 the line bends up slightly and when d=4 the line bends down a lot. So d is somewhere between 0 and 4. Find d to 1dp. (3) extrapolate that straight line to M = 0, and note the resulting intercept on the vertical axis, which is equal to In(20) to find the roughness length Zo- (4) pick any point exactly on the plotted line, and then plug in its M and z values, along with the d and zo values just found, to calculate u* using equation above. The displacement distance, d, is m The roughness length, zo, is m The frictional velocity, u*, is m s¹.