Cold-air pools in the northern sector of Coimbra: an integrated analysis of the topoclimatologic dynamics and implications for spatial planning

Abstract

This article presents an integrated analysis of the dynamics of cold-air pools in three valleys located in the northern sector of Coimbra (Coselhas, Eiras, and the Souselas/Fornos depression), based on three previously published individual studies. The phenomenon forms exclusively under anticyclonic conditions, through radiative cooling and katabatic drainage from the surrounding slopes, and develops in three distinct phases: formation, intensification, and dissipation. Seasonal analysis, conducted exclusively in the Eiras valley, confirmed the primarily winter character of the phenomenon, which is absent under overcast conditions and during the summer. The vertical structure was characterized using UAV-based surveys, which identified well-defined thermal inversions in all valleys, with inversion top altitudes reflecting the specific morphological characteristics of each depression. The three valleys exhibit distinct functional profiles—consolidated urban, peri-urban in transition, and rural-industrial—with differentiated implications for spatial planning. The study highlights the need to integrate topoclimatology into territorial management instruments and to implement air quality monitoring systems in valley bottoms.