Cold Pool‐Land Surface Interactions in a Dry Continental Environment

Abstract

Cold pools influence convective initiation and organization, dust lofting, and boundary layer properties, but little is known about their interactions with the land surface, particularly in dry continental environments. In this study, two‐way cold pool‐land surface interactions are investigated using high‐resolution idealized simulations of an isolated, transient cold pool evolving in a dry convective boundary layer. Results using a fully interactive land surface demonstrate that sensible heat fluxes are suppressed at the center of the cold pool but enhanced at the edge due to the spatial patterns of land surface cooling and the air temperature and wind speed perturbations. This leads to cold pool dissipation from the edge inward. Latent heat fluxes are primarily suppressed within the cold pool, and the magnitude of this suppression is controlled by competition between atmospheric and land surface effects. By comparing the fully interactive land surface simulation to a simulation with imposed surface fluxes, the land surface‐cold pool feedbacks are shown to reduce the cold pool lifetime, extent, and intensity by up to 50% and influence the pattern of boundary layer turbulent kinetic energy recovery, which have significant implications for cold pool‐induced convective initiation.

Mechanical Forcing of Convection by Cold Pools: Collisions and Energy Scaling

“…More comprehensive studies with moist CP dynamics will allow to verify these conclusions and test against similar findings from numerical studies, stating a linear relation between maximum precipitation intensity and the CP strength in terms of its radial velocity (Fournier & Haerter, 2019). The scaling of CP expansion with potential energy furthermore may assist a better understanding of the kinetics and internal vortical circulation of CPs, which play a crucial role in the mechanical forcing during CP collisions (Cafaro & Rooney, 2018) and are important factors for CP dissipation (Grant & van den Heever, 2016, 2018; Romps & Jeevanjee, 2016; Rooney, 2018).…”

Particle‐Based Tracking of Cold Pool Gust Fronts

“…Thus, the area of CPs identified by temperature‐based methods tends to reduce during later stages of the CP lifetime (Feng et al, ). This retreating feature stands in contradiction to the dynamics of CP gust fronts, which often continue to spread by inertia, even if the temperature anomaly is reduced (Fournier & Haerter, ; Grant & van den Heever, ). Thus, if we are interested in the mechanical triggering of convective triggering, it is useful to define the CP as the area confined by the band of strong horizontal convergence near the surface.…”

The Dynamical Coupling of Convective Updrafts, Downdrafts, and Cold Pools in Simulated Supercell Thunderstorms

“…Our focus on cold pool depth is based in part on the aforementioned finding that it relates best to the strength (and depth) of gust frontal updrafts, and accordingly is a key parameter in cold pool parameterizations (Del Genio et al, ; Grandpeix & Lafore, ). It also relates to the time scale for elimination of the cold pool and its surface‐based convective inhibition (Del Genio, ; Drager & van den Heever, ; Grant & van den Heever, , ; Trapp & Woznicki, ). Our inclusion of updraft and downdraft widths, and their relation to environmental conditions, is based in part on the desire to possibly identify additional constraints that can help improve convective parameterization schemes (Grandpeix & Lafore, ; Hourdin et al, ).…”