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

How weakened cold pools open for convective self-aggregation

Silas Boye Nissen1 and Jan O. Haerter1,2,3
Silas Boye Nissen and Jan O. Haerter
  • 1Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark (
  • 2Physics and Earth Sciences, Jacobs University Bremen, Bremen, Germany.
  • 3Complexity and Climate, Leibniz Center for Tropical Marine Research, Bremen, Germany.

In radiative-convective equilibrium (RCE) simulations, convective self-aggregation (CSA) is the spontaneous organization into segregated cloudy and cloud-free regions. Evidence exists for how CSA is stabilized, but how it arises favorably on large domains is not settled. Using large-eddy simulations (LES), we link the spatial organization emerging from the interaction of cold pools (CPs) to CSA. We systematically weaken simulated rain evaporation to reduce maximal CP radii, Rmax, and find reducing Rmax causes CSA to occur earlier. We further identify a typical rain cell generation time and a minimum radius, Rmin, around a given rain cell, within which the formation of subsequent rain cells is suppressed. Incorporating Rmin and Rmax, we propose a toy model that captures how CSA arises earlier on large domains: when two CPs of radii ri,j ∈ [Rmin, Rmax] collide, they form a new convective event. These findings imply that CPs play a crucial role in RCE simulations by preventing the onset of CSA.

How to cite: Nissen, S. B. and Haerter, J. O.: How weakened cold pools open for convective self-aggregation, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1520,, 2021.

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