The air temperature distribution and airflow field in an actual urban street canyon were clarified through intensive observations. The 2-D distribution of temperature and wind was clarified on a N-S vertical cross section of the E-W-oriented street canyon. A steady single vortex, approximately equal to the size of the canyon, was frequently observed. A rather distinct vortex was observed when the ambient winds above the canyon were high and their direction was transverse to the canyon. Thermally unstable stratification also contributed to the formation of the distinct vortex. The vortex airflow advected the cold air mass, which was produced by the shade due to the buildings, upwind of the ambient wind above the canyon.
2008 by the Meteorological Society of Japan