The role of low-level clouds in the West African monsoon system

Kniffka, Anke; Knippertz, Peter; Fink, Andreas H.

doi:https://doi.org/10.5194/acp-19-1623-2019

Articles | Volume 19, issue 3

https://doi.org/10.5194/acp-19-1623-2019

© 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-19-1623-2019

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

Articles | Volume 19, issue 3

Research article

|

07 Feb 2019

Research article |

| 07 Feb 2019

The role of low-level clouds in the West African monsoon system

Anke Kniffka, Peter Knippertz, and Andreas H. Fink

Supplement

https://doi.org/10.5194/acp-19-1623-2019-supplement

Data sets

TRMM (TMPA) Rainfall Estimate L3 3 hour 0.25 degree x 0.25 degree V7 Tropical Rainfall Measuring Mission (TRMM) https://doi.org/10.5067/TRMM/TMPA/3H/7

GPCP Version 1.2 One-Degree Daily Precipitation Data Set G. J. Huffman, D. T. Bolvin, and R. F. Adler https://doi.org/10.5065/D6D50K46

Surface Radiation Data Set - Heliosat (SARAH) – Edition 2 Uwe Pfeifroth, Steffen Kothe, Richard Müller, Jörg Trentmann, Rainer Hollmann, Petra Fuchs, and Martin Werscheck https://doi.org/10.5676/EUM_SAF_CM/SARAH/V002

CM SAF TOA Radiation GERB/SEVIRI Data Record – Edition 2 Nicolas Clerbaux, Manon Urbain, Alessandro Ipe, Edward Baudrez, Almudena Velazquez-Blazquez, Tom Akkermans, Rainer Hollmann, Petra Fuchs, Nathalie Selbach, and Martin Werscheck https://doi.org/10.5676/EUM_SAF_CM/TOA_GERB/V002

Surface Irradiances of Edition 4.0 Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Data Product (https://doi.org/10.5067/Terra+Aqua/CERES/EBAF-Surface_L3B004.0) S. Kato, F. G. Rose, D. A. Rutan, T. J. Thorsen, N. G. Loeb, D. R. Doelling, X. Huang, W. L. Smith, W. Su, and S. Ham https://doi.org/10.1175/JCLI-D-17-0523.1

Clouds and the Earth's Radiant Energy System (CERES) Energy Balanced and Filled (EBAF) Top-of-Atmosphere (TOA) Edition-4.0 Data Product (https://doi.org/10.5067/Terra+Aqua/CERES/EBAF-TOA_L3B004.0) N. G. Loeb, D. R. Doelling, H. Wang, W. Su, C. Nguyen, J. G. Corbett, L. Liang, C. Mitrescu, F. G. Rose, and S. Kato https://doi.org/10.1175/JCLI-D-17-0208.1

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Short summary

The role of low-level clouds in the southern West Africa (SWA) energy balance and the West African monsoon system is assessed via targeted sensitivity studies with the NWP model ICON. We show for the first time that rainfall over SWA depends logarithmically on the optical thickness of low clouds, as these control the diurnal evolution of the planetary boundary layer, vertical stability and finally convection. Small variations in clouds or aerosol have a substantial impact on precipitation.