Variation of Wind Profiles near Ground During Typhoon "Muifa"

Wind profiles of typhoon 'Muifa' are analyzed based on the long-term measured data collected respectively at 10,20,30 and 40 meters high from the ground in Pudong New Area of Shanghai.The height of neutral atmospheric boundary layer(ABL) increases with wind speed.The average height of neutral ABL during typhoon 'Muifa' is 2 063 m by calculation,which greatly exceeds the gradient height(350 m) recommended by Chinese National Load Code(GB50009 —2001,2002) for open terrain.The stability parameter z/L is almost within [-0.1,0.1] when the wind speed becomes high,which means near-neutral flow.Measured mean wind speed profile agrees well with the power law,the log law and Deaves-Harris ABL model.Based on the expression form in ASCE7-10,the fitting equations of turbulence intensity profiles in longitudinal,lateral and vertical directions are presented.Finally,the formulas for gust factors are also derived using curve-fitting technique,which can provide reference for engineering designing.