Observation of wind profile and analysis of atmosphere boundary layer in urban areas

The results of statistical analysis of the wind speed and temperature data observed at the heights of 8 to 320 m from the Beijing meteorological tower on March 20, 2002 are presented. The results revealed that the average ground roughness length is about 1.5 m and zero-plane displacement is about 17.5 m at the tower site. The wind speed profiles and direction profiles exhibited ″kinks″ at the height of 47 m, 100 m, or 200 m. The direction at 100 m exhibited a clockwise rotation relative to the direction at 8 m. The average α for considering or omitting the zero-plane displacement were 0.278 and 0.348, with the standard deviations of 0.052 and 0.063, respectively. Both average α were found to decrease with the increase of the mean wind speed. The profile of the mean wind speed could be described by the power law and D-H model fairly well, while the scope of application of the log law was only 200 m under strong wind conditions. There was a little difference of the ratio of turbulence intensities from the field measurements with those from using the empirical formula, and the I_v/I_u and I_w/I_u became larger with the increase of height.