资源环境科技发展态势分析平台

The impact of cold pools on line-orientated convective systems is assessed using idealized simulations of tropical oceanic convection under weak, moderate, and strong wind shear regimes. Cold pools are weakened by suppressing evaporation in the shallow subcloud layer. Analysis of objectively identified convective systems reveals that the convection with weaker cold pools is more often oriented parallel, rather than perpendicular, to the wind shear. The cold pool-induced orientation changes are most pronounced in the strong shear environment. Interactions between convective orientation and the tropical atmosphere are assessed. Simulations with shear-parallel convection demonstrate more top-of-atmosphere upwelling longwave radiation and less reflected shortwave radiation due to changes in convective anvils, faster-propagating larger-scale gravity waves, narrower cross-shear moisture distributions, and differences in convective momentum fluxes. The results highlight critical interactions across convective scales, mesoscales, and climate scales, as well as avenues for parameterizing structural modes of mesoscale-organized convection in global models.

Plain Language Summary Over tropical oceans, individual thunderstorms often cluster together into a collection of thunderstorms. The way in which these thunderstorm clusters are organized is important for many aspects of weather and climate. For example, for line-organized thunderstorm clusters, whether the line is oriented parallel or perpendicular to the winds is important for how the thunderstorms alter the winds and how their anvils reflect solar radiation. In this study, we investigate the influence of cold pools, which are evaporatively cooled regions of air near the surface below thunderstorms, on the orientation of line-organized thunderstorm clusters using computer model simulations. We find that line-organized thunderstorm clusters are oriented parallel to the winds more often when the cold pools are weaker. We also show that cold pools have a larger impact on the orientation of the thunderstorm line when the upper level winds are stronger. Finally, we show how the cold pool-induced changes to line-organized thunderstorms affect the tropical climate, meaning these effects are important for climate models.