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Sensitivity of shallow cumulus and deeper shallow cumulus (congestus) in subsiding branches of large-scale circulations

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Wednesday, 21 September 2016, 12:00

Wednesday, September 21, 2016. 12:00 PM. Sensitivity of shallow cumulus and deeper shallow cumulus (congestus) in subsiding branches of large-scale circulations . Louise Nuijens, MIT. Sponsored by NOAA Geophysical Fluid Dynamics Laboratory. More information here 

 

Shallow clouds have received much attention in recent years for their role in the uncertainty of climate sensitivity, related to their influence on Earth's albedo. In particular, climate models diverge in their modeled behavior of shallow cumuli in regions with weak subsidence - areas which cover much of the subtropical and tropical ocean. It is also increasingly recognized that shallow clouds and the convection that underlies them might influence the climate system in other important ways, such as through circulations tied to regions of deep convection. In this talk I will use a long record of atmospheric profiling at the edge of the subtropics and tropics to show that cloudiness from shallow cumuli is rather insensitive to changes in the large-scale flow. I will discuss how shallow cloud behaves differently in and among climate models, and hence why climate-model cloud feedbacks might be overestimated. Furthermore, I will show that deeper modes of shallow cumuli or congestus, which readily precipitate, have greater variability.

Location  Smagorinsky Seminar Room, GFDL, Princeton, NJ