Weak and intense katabatic winds: impacts on turbulent characteristics in the stable boundary layer and CO₂ transport

Abstract

Abstract. The role of thermally-driven local downslope or katabatic flows in the dynamics and turbulent features of the stable boundary layer (SBL) is investigated using observations. Measurements are carried out in a relatively flat area 2-km away from the steep slopes of the Guadarrama Mountain Range (Spain). Forty katabatic events are selected from an observational database spanning the 2017-summer period, by using an objective and systematic algorithm that is able to account for local and synoptic forcings. We subsequently classify the katabatic events into weak, moderate and intense according to the observed maximum wind speed. This classification enables us to contrast the main differences in dynamics and thermal structure. We find that the stronger katabatic events are associated with an earlier onset time of these flows. We relate it to very low soil-moisture values (