Experimental study of turbulence and vertical temperature profile in the urban boundary layer
We observed the turbulence and vertical profile of temperature in and above the roughness sublayer (RS) using a tower, a tethered balloon and a Doppler sodar in Himeji City. A 3–D ultrasonic anemometer–thermometer was sited at a height of 54 m on the tower. The present results showed that in the RS, the ratio of friction velocity to wind speed, u* /u, observed under unstable conditions of −4.2 < z′/L < −0.5 were close to those under neutral conditions, where z′ = z − d; the displacement height of d = 2 m; L is the Monin–Obkhov stability length. In addition, σw/u* were lower than the universal function presented by Panofsky et al. (1977). The cross correlation coefficients for u′w′ and T′w′ under neutral and unstable conditions were also studied.
Keywords: correlation coefficient, Doppler sodar, field observation, Monin–Obukhov similarity theory, roughness sublayers, towers, turbulence, unstable conditions, urban areas, vertical temperature profile, urban boundary layers, friction velocity, wind speed, air pollution, air quality, dispersion modelling