Nocturnal low-level clouds in the atmospheric boundary  layer over southern West Africa: an observation-based  analysis of conditions and processes

Adler, Bianca; Babić, Karmen; Kalthoff, Norbert; Lohou, Fabienne; Lothon, Marie; Dione, Cheikh; Pedruzo-Bagazgoitia, Xabier; Andersen, Hendrik

doi:https://doi.org/10.5194/acp-19-663-2019

Articles | Volume 19, issue 1

https://doi.org/10.5194/acp-19-663-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Results of the project "Dynamics–aerosol–chemistry–cloud...

https://doi.org/10.5194/acp-19-663-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 1

Research article

|

17 Jan 2019

Research article |

| 17 Jan 2019

Nocturnal low-level clouds in the atmospheric boundary layer over southern West Africa: an observation-based analysis of conditions and processes

Bianca Adler, Karmen Babić, Norbert Kalthoff, Fabienne Lohou, Marie Lothon, Cheikh Dione, Xabier Pedruzo-Bagazgoitia, and Hendrik Andersen

Data sets

DACCIWA field campaign, Savè super-site, UPS instrumentation S. Derrien, Y. Bezombes, B. Bret, O. Gabella, C. Jarnot, P. Medina, E. Piques, C. Delon, C. Dione, B. Campistron, P. Durand, C. Jambert, F. Lohou, M. Lothon, F. Pacifico, F., and Y. Meyerfeld https://doi.org/10.6096/dacciwa.1618

DACCIWA field campaign, Savè super-site, Cloud and precipitation J. Handwerker, S. Scheer, and T. Gamer https://doi.org/10.6096/dacciwa.1686

DACCIWA field campaign, Savè super-site, Surface measurements M. Kohler, N. Kalthoff, J. Seringer, and S. Kraut https://doi.org/10.6096/dacciwa.1690

DACCIWA field campaign, Savè super-site, Thermodynamic data sets A. Wieser, B. Adler, and B. Deny https://doi.org/10.6096/dacciwa.1659

Short summary

This study deals with nocturnal stratiform low-level clouds that frequently form in the atmospheric boundary layer over southern West Africa. We use observational data from 11 nights to characterize the clouds and intranight variability of boundary layer conditions as well as to assess the physical processes relevant for cloud formation. We find that cooling is crucial to reach saturation and a large part of the cooling is related to horizontal advection of cool air from the Gulf of Guinea.