Thermal and air flow characteristics in a deep pedestrian canyon under hot weather conditions

The present paper reports the results of a specific experiment carried out in a deep pedestrian canyon in Athens, Greece. The air flow inside and outside the canyon as well as the air and surface temperatures inside the canyon are measured for a period of seven continuous days during the whole day and night period. The air flow characteristics inside the canyon are analyzed. For perpendicular wind speeds, the air flow inside the canyon is characterized by either a circulatory vortex driven by the ambient air flow or a double vortex flow where the upper one is driven by the ambient air flow and the lower one is driven in the opposite direction by the circulation above. When the ambient air blows parallel to the canyon, the measured wind data inside the canyon indicate a flow in the same direction. When the air flows at a certain angle to the canyon axis, the measured data indicate that a spiral vortex is induced along the canyon length. The spatial and temporal variation of the surface and air temperature distribution inside the canyon is analyzed. The heat island intensity in the canyon is estimated based on measurements from a reference station.