Probing Cold Pool Dynamics using a Lagrangian Particle Model

Abstract:

Cold pools are fundamental ingredients of deep convection. They contribute to organizing the sub-cloud layer and are considered key elements in triggering new convective cells. Suitable diagnostics applied to numerically simulated cold pools offer a great opportunity to gain much information on these structures. We have previously used Lagrangian tracking to study the mechanisms through which cold pools trigger new convective cells in a case of radiative-convective equilibrium, and found that particles reach their level of free convection through a cooperation between gust front lifting and thermodynamic forcing. We have further used Lagrangian methods to investigate the dynamics of the unsaturated downdrafts which give rise to cold pools, and will show that they originate at very low altitudes and condensate loading plays a much bigger role than rain evaporation in maintaining such downdrafts. Finally, we will also explore how the Lagrangian tracking can be used to study entrainment of boundary layer air in the gust front of cold pools and quantify its importance for cold pool recovery compared to surface fluxes.