Characteristics of Organized Deep Convection in the Tropical Atlantic

Over the tropical oceans, the large-scale, meridional circulation drives the accumulation of moist and warm air, leading to a relatively narrow, convectively active band that interacts with this heteorogeneous environment. Furthermore and possibly due to self-aggregation feedbacks, deep moist convection clusters and organizes into multi-scale structures that strongly impact the hydrological cycle and Earth's radiation budget. Therefore, the current study focusses on deep moist convection the tropical Atlantic region and combines satellite observations with large-domain, storm-resolving simulations that have been performed in support to the NARVAL I and II campaigns. Deep convective cells are identified with object-based techniques and analyzed with respect to their structural behavior and spatial arrangement. We show that cloud size distributions derived from observations as well as simulation follow a similar power law behavior, possibly an imprint of similar spatial-scale interactions. Using pair-correlation analysis, we quantify the organizational state and confirm that, in general, tropical deep convective cells are organized into clusters. We additionally show that the spatial arrangement of larger cells deviates much more from randomness than that of smaller cells which might be related to their stronger dynamical feedbacks. Using arguments from statistical physics, we finally discuss the consequences of the clustering of deep convective cells considering an effective interaction potential and the stability of the inter-tropical convergence zone.