The importance of topography in the formation of cold-air pooling in urban spaces. The example of the city of Coimbra (Portugal)

Abstract The aim of this paper is to analyze the existence cold-air pools on anticyclonic nights in a narrow urban valley where three hospital units and road with intense traffic are located slopes associated proximity medium-size mountain introduce different factors from that observed other valleys phenomenon forms cold, calm nights. On these nights, it develop just after sunset, opposition ridge dominates (thermal belts), found their formation, development, disappearance first hours day daily phenomenon. Using fixed data loggers portable surface at altitude coupled UAV (drone), was possible calculate variation air temperature (as well as locate inversion layer) sectors defined along valley. finding oscillation longitudinal profile altitude, reflects double source feeding: in-situ irradiation, draining down massif.