Evaluation of Trade Wind Mesoscale Morphology Evolution and Transitions

Mesoscale cloud morphology patterns in the trade-winds can be grouped by their distinct appearance, size, and radiative properties into four categories: Sugar, Gravel, Flowers, and the synoptically driven Fish. Two occurrence pathways for the larger boundary-layer cloud organization structures were observed during the wintertime 2020 EUREC⁴A-ATOMIC joint campaign: i) regional Gravel persistence and ii) transitions to Gravel and Flowers from smaller Sugar clouds. Understanding the contributions to larger cloud structure occurrence under pathways of persistence vs. transitions from smaller clouds has utility in predicting their occurrence under climate change. Two EUREC⁴A-ATOMIC case studies are developed for these respective pathways during multi-day periods when observational platforms were longitudinally distributed across the ocean in parallel with Barbados. A Lagrangian analysis framework is developed by using for/backward 30-hr boundary layer trajectories initialized every 3-hr from the RV Ronald H. Brown (i.e., the mid-evolution reference platform) to connect upwind (e.g., the Northwest Tropical Atlantic Station buoy) and downwind (e.g., the Barbados Cloud Observatory) platforms. This synergistic, multi-platform campaign dataset is supplemented with satellite observations and reanalysis. Motion-stabilized Doppler-lidar observations at the RV Ronald H. Brown and the Barbados Cloud Observatory allow us to examine characteristics of cloud and plume dynamics in addition to the impact of environmental conditions expected to influence cloud organization and development (e.g., surface wind speeds, energy and moisture fluxes, stability, entrainment, large- and meso-scale subsidence, and aerosols). Eulerian differences between key platforms over the campaign period are evaluated and campaign findings are further extended using multi-year Lagrangian analysis.