An Observational and Multi-Scale Modeling Framework (MMF) Depiction of the Transition from Light Rain to Deep Convection on Sub-Daily Timescales

A number of modeling studies have shown that cold pools can serve as triggering mechanisms for the development of deep, organized convection. Recognizing the important role they may play, recent studies have attempted to parameterize their effects (e.g. density current parameterizations, increases in turbulent kinetic energy, etc.) on convective development in coarse-resolution global models. From an observational perspective, the evolution of cold pool activity and rainfall has been limited to field campaigns and in situ radar analyses. In this study, a first attempt at observing cold pool activity from a satellite perspective (spanning all tropical ocean basins from 30S-30N latitude) is undertaken. Co-locating several observational products for rainfall, moisture, atmospheric buoyancy and newly derived triggering energy related to mesoscale cold pool activity, a study of the sub-daily transition from light rainfall to deep convection at a spatial scale of 100-200 km is performed. The transition, as simulated in a version of the super-parameterized (SP-) Community Atmosphere Model (CAM) developed at Colorado State University, is evaluated against the observational depiction. The extent to which the sub-daily temporal evolution of rainfall in both the observations and MMF can be explained by a relationship between convective inhibition (CIN), cold pool triggering energy and moisture is discussed and compared to current hypotheses that serve as the foundations for parameterizations relating these parameters to convection development.