BOUNDARY-LAYER EVOLUTION OVER A LARGE AND BROAD MOUNTAIN BASIN

In this study observations of the vertical structure of the Atmospheri c Boundary Layer (ABL), recorded at a broad mountainous valley are pre sented. The vertical profiles of temperature, wind speed and direction up to a height of about 800 meters over the valley bottom have been m easured and the temporal evolution of ABL structure of the area has be en studied. Specifically, the mechanism of nocturnal inversion destruc tion during morning hours has been studied, which is of major importan ce in the study of the dispersion of air pollutants over the area. The se observations suggest that the break up of nocturnal inversion durin g morning hours is mainly caused by a combined mechanism, the build up of the Convective Boundary Layer (CBL) and the presence of upslope wi nds, resulting to a continuous descent of the top of the nocturnal inv ersion.