5–7 May 2021
virtual
Europe/Copenhagen timezone

How weakened cold pools facilitate convective self-aggregation

6 May 2021, 16:00
1h 45m
virtual

virtual

Interactive presentation RCE and Processes in Deep Convective Organization RCE and Processes in Deep Convective Organization

Speaker

Mr Silas Boye Nissen (Niels Bohr Institute)

Description

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, $R_{\text{max}}$, and find reducing $R_{\text{max}}$ causes CSA to occur earlier. We further identify a typical rain cell generation time and a minimum radius, $R_{\text{min}}$, around a given rain cell, within which the formation of subsequent rain cells is suppressed. Incorporating $R_{\text{min}}$ and $R_{\text{max}}$, we propose a toy model that captures how CSA arises earlier on large domains: when two CPs of radii $r_{i,j}\in[R_{\text{min}},R_{\text{max}}]$ collide, they form a new convective event. These findings imply that interactions between CPs may explain the initial stages of CSA.

Primary author

Mr Silas Boye Nissen (Niels Bohr Institute)

Co-author

Jan Haerter (Niels Bohr Institute, Copenhagen University)

Presentation materials