Investigation of cold-air drainage events during the night over undulating terrain




Cold-air flow, Surface slope, Stable conditions


The aim of the work is to investigate the possibility of cold air drainage flows over gently undulating terrain with a grassland cover. Such type of landscape is found in southern Brazil, Uruguay, and Argentina. Drainage flows have been reported in previous studies and seem to happen over a wide range of scales of topographic features. Under stable atmospheric conditions, thin-cold air layers may form and accumulate over the surface. If the surface is sloped, the weight can exceed the local vertical pressure gradient causing the cold air to acquire a negative buoyancy and flow down the slope. Such flows make the cold air to accumulate at the lower parts of the terrain. In the work, we analyze temperature, wind, and longwave radiation data collected at a micrometeorological. During several occasions is observed that the flow near the surface, at levels below 4 m, follows the direction of the slope, while the flow above follows different directions. Such events have wind speeds less than 1 ms-1 and happens when the flow at the top of the tower (30 m) is less than 4 ms-1.


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Author Biographies

Luiz Eduardo Medeiros, Universidade Federal do Pampa

Doutor em Ciências Atmosféricas.

Maicon Fonseca Andrades, Universidade Federal de Santa Maria

Ph.D Student 

Otávio Costa Acevedo, Universidade Federal de Santa Maria

Associate Professor (Physics Department)

Débora Regina Roberti, Universidade Federal de Santa Maria

Associate Professor of the Physics Department 

Thiago Ferreira Gomes, Universidade Federal do Pampa

Master Student

Gilberto Fisch, Universidade de Taubaté

Professor of the Taubaté University 

Felipe Denardin Costa, Universidade Federal do Pampa

Associate Professor 

Rafael Maroneze, Universidade Federal do Pampa

Adjunct Professor 


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How to Cite

Medeiros, L. E., Andrades, M. F., Acevedo, O. C., Roberti, D. R., Gomes, T. F., Fisch, G., Costa, F. D., & Maroneze, R. (2023). Investigation of cold-air drainage events during the night over undulating terrain. Ciência E Natura, 45(esp. 2), e77188.

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