The nocturnal boundary layer of Aburra’s valley, a tropical urban area with complex topography

The atmospheric processes that affect the Nocturnal Boundary Layer (NBL) raise unresolved questions, more critical in the case of urban, tropical, and mountainous areas. This research examines the structure of the NBL in the Aburrá Valley - Colombia, a tropical and urbanized region characterized by complex topography. Here six methods were used to estimate the thickness of the NBL, considering the minimum backscattering gradient method (based on ceilometer data) as a reference. Although all the methods contribute to the understanding of the NBL, it was found that the Critical Richardson Number equal to 0,5 fits the best to the reference method, at least for the year 2017, indicating that the tops of the NBL were below the peaks of the surrounding mountains. These results provide technical arguments to consider in managing urban air quality in Valle de Aburrá and other urban, tropical, and mountain areas