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Detecting Cold Pool Family Trees in Convection Resolving Simulations
  • Jannik Hoeller,
  • Romain Fiévet,
  • Jan O Haerter
Jannik Hoeller
Leibniz Centre for Tropical Marine Research

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Romain Fiévet
Niels Bohr Institute, University of Copenhagen
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Jan O Haerter
Leibniz Centre for Tropical Marine Research
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Abstract

Recent observations and modeling increasingly reveal the key role of cold pools in organizing the convective cloud field. Several methods for detecting cold pools in simulations exist, but are usually based on buoyancy fields and fall short in reliably identifying the active gust front. The current algorithm, termed CoolDeTA, aims to detect and track cold pools along with their active gust fronts and the “offspring” rain cells generated nearby. We show how CoolDeTA can reconstruct cold pool family trees. Using it allows us to contrast RCE and diurnal cycle cold pool dynamics, as well as cases with vertical wind shear and without. The results suggest a conceptual model where cold pool triggering of children rain cells follows a simple birth rate, which is proportional to a cold pool’s gust front length. The proportionality factor depends on the ambient atmospheric stability and is lower for RCE, in line with marginal stability as traditionally ascribed to the moist adiabat. In the diurnal case, where ambient stability is lower, the birth rate thus becomes substantially higher, in line with periodic insolation forcing — resulting in essentially run-away mesoscale excitations generated by a single parent rain cell and its cold pool.
28 Feb 2023Submitted to ESS Open Archive
01 Mar 2023Published in ESS Open Archive