Turbulent winds at the height of 100m over the city of Tokyo

Abstract

Measurements of turbulent winds were made at the height of about 100m over the city of Tokyo. Power spectra, intensities of turbulence, gust factors and peak factors were calculated and were classified in terms of wind speeds, wind directions, weather conditions and day or night.Gust factors and intensities of turbulence decreased with wind speed and varied with weather condition by day and night though they were nearly constant in the range of wind speed more than 7-8 m/s without relation to weather conditions and day and night. Gust factors were nearly equal to 1.40 to 1.42 in this range of wind speed. In clear night, gust factors and intensities of turbulence were not depend on wind speed. On the other hand, peak factors were almost independent of wind speed, weather condition and day and night, and nearly equal to 2.7 to 3.0.Power spectra in strong wind conditions were able to be approximately expressed by the equation suggested by Fichtl and McVehil (1970). The integral scale obtained from the above approximation was about 384m under the frozen turbulence hypothesis.