Sea-Breeze and Topographic Influences on the Planetary Boundary Layer in the Coastal Upwelling Area of Cabo Frio (Brazil)

We use a fully coupled oceanic-atmospheric model to investigate the sources and sinks of turbulent kinetic energy in the Cabo Frio coastal area and to determine the role of topography and the sea breeze in planetary boundary-layer (PBL) development. The study area presents similar boundary-layer characteristics than other coastal upwelling areas with complex topography, such as increased stability and low-level jets. The results show that the major effect of upwelling, over the investigated area, is to maintain low temperatures in the lower atmosphere over the coastal zone, sustaining a strong temperature inversion that precludes the vertical PBL development. Therefore, the cooling effect reduces the horizontal thermal contrast between land and water, generating a negative feedback between the intensity of the sea breeze and the intensity of the upwelling. The topography at Cabo Frio prevents this cooling effect from propagating inland, since it limits the penetration of the sea-breeze circulation.