The utility of SODAR measurements for understanding power performance is more apparent when considering turbulent intensity. Power curves for Turbine 1 were stratified by nacelle cup anemometer I U and SODAR I U in figure 5. Stratification by nacelle I U (figure 5(a)) included stable or strongly stable periods (I U < 10%) and convective or strongly convective periods (I U > 13%). Too few **data** points were available to isolate the effects of strongly convective conditions for the nacelle-based parameter. Observed power yields followed the expected power curve regardless of stability class. Power differences were less than 5% and occurred when the nacelle 'true-flux' equivalent wind speed was between 4 and 7 m s −1 .