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LLLJP Wind and Turbulence

turbulence intensity

Turbulence intensity, plotted against the horizontal wind speed for the night of September 5. Solid line is a second degree polynomial fit.

Wind and turbulence flow at heights of the turbine-rotor

Composite profiles for the night of September 15 are below, showing (from the left to the right) wind speed UH, streamwise variance σU, and turbulence intensity TI (σU/UH), show a strong turbulence below the height of the LLJ maximum. All heights are normalized by the height of the LLJ maxima (ZC).

wind and turbluence composite profiles

Distribution of the wind speed (top) show a greater wind resource potential for the layers of 45-200 m, and 45-250 m compare to the layer of 45-115 m currently occupied by turbine rotors. Standard deviation (middle) and turbulence intensity (bottom) also increase for the thicker layers and the shapes of distributions changed from (blue) normal to (red and green) skewed.

wind and turbluence composite profiles

Wind shear across the rotor layer

Profiles of mean horizontal velocity composited for each night of HRDL observations during LLLJP, showing almost linear wind shear up to 100-200 m.

wind shear profiles

Distributions of the shear exponent (α) computed by lidar horizontal velocities measured at 115, 200, 250 and reference velocity at 20 m for the entire period of HRDL observations. In most cases α>0.20, with a dominant mode of 0.30-0.36.

wind shear distributions

Time-series of the lidar (pluses) and high-confidence sodar (diamonds) wind speed measured at 200 m AGL and computed using the power law with a shear exponent of (solid) 0.30, (dashed) 0.40, and (dotted) 0.20 with a reverence wind speed measured by lidar at 20 m. Data shown for the night of September 15.

wind shear time-series