Measurement of Roughness Length in an Urban Area

Abstract

Roughness length was measured over the urban building canopy in Shibuya Tokyo. The study area includes low residential and highly built-up buildings. A sonic anemometer mounted in the tower at 52 m AGL measured turbulence, and the roughness length was determined by using the log profile equation and the measured wind speed. The measured roughness length agreed qualitatively with the land-cover type; 1.2 m for highly built-up area and 0.6 m for lower residential area. The parameterization for roughness length developed by Kanda et al. (2014, Boundary-Layer Meteorology) was validated with the measured results. Although some uncertainty remains for the footprint size, the parameterization agreed with the measurement.