The puzzle of shallow convection-circulation coupling

Since shallow clouds over the tropical oceans are organised into mesoscale structures, explaining the role of these clouds in climate requires understanding what governs mesoscale patterns in shallow cumulus convection. Many puzzle pieces have emerged in recent years. These include both external forcings on the boundary layer, such as the import of extratropical eddies and water vapour with the large-scale flow, weak sea-surface temperature anomalies and remotely triggered gravity waves, as well as internal feedbacks between convection and its mesoscale environment, such as cold pool dynamics and self-reinforcing low-level moisture convergence. What all these mechanisms share, is their interaction with the low-level mesoscale vertical motion field, which itself is often organised into shallow circulations that couple tightly to the convection. Here, we will therefore propose to begin assembling the puzzle pieces by analysing the origins of shallow circulations, in a conceptual framework of weak mesoscale virtual temperature gradients. The analysis is enabled by the simultaneous presence of observations of clouds, thermodynamics and mesoscale vertical motion taken during the EUREC4A field campaign, and simulations from EUREC4A-MIP; it will therefore serve as an example of what other puzzle pieces might fall in place by combining observations with other intercomparison projects in the model hierarchy, such as Lagrangian LES MIP, CP-MIP and NextGEMS.