EGU General Assembly 2021
© Author(s) 2021. This work is distributed under
the Creative Commons Attribution 4.0 License.

Why sometimes its simply sunny (in the trades)

Bjorn Stevens1, Ilya Serikov1, Anna Lea Albright2, Sandrine Bony2, Geet George1, Lutz Hirsch1, Friedhelm Jansen1, Tobias Kölling1, Hauke Schulz1, Raphaela Vogel2, and Ludwig Worbes1
Bjorn Stevens et al.
  • 1Max Planck Institute for Meteorology, Director, Atmosphere in the Earth System, Hamburg, Germany (
  • 2Laboratoire de Meteorologie Dynamique (LMD/IPSL), Paris, France

Cloud free skies are rare in the trades.  We analyze conditions in which cloud-free conditions prevail.  For this purpose Raman water vapor measurements from the Barbados Cloud Observatory, complemented by ship-based measurements during EUREC4A are used to explore water vapor variability in the marine boundary layer.   We explore the consistency of the inferred cloud base height with estimates of temperature and water vapor from the lidar signal, and examine the co-variability of these quantities.  After having established the properties of these measurements, we seek to use them as well as others, to explain in what ways periods of cloud-free conditions are maintained, investigating the hypothesis that only when the wind stills is it simply sunny.

How to cite: Stevens, B., Serikov, I., Albright, A. L., Bony, S., George, G., Hirsch, L., Jansen, F., Kölling, T., Schulz, H., Vogel, R., and Worbes, L.: Why sometimes its simply sunny (in the trades), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15408,, 2021.


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