From Sugar to Flowers: A Transition of Shallow Cumulus Organization During ATOMIC

The Atlantic Tradewind Ocean-Atmosphere Mesoscale Interaction Campaign (ATOMIC) took place in January–February, 2020. It was designed to understand the relationship between shallow convection and large-scale environment trade-wind regime. A Lagrangian large eddy simulation, following trajectory of a boundary-layer airmass, can reproduce transition trade cumulus organization from “sugar” “flower” clouds with cold pools, observed on February 2–3. simulation is driven reanalysis meteorology, in-situ aerosol data ATOMIC its joint field study EUREC4A. During transition, upward motion deepens cloud layer. total water path optical depth increase, especially moist regions where flowers aggregate. This due mesoscale circulation that renders net convergence already cloudy regions, strengthening organization. An additional shows stronger scale reinforces accelerates process by cloud-layer buoyant turbulence kinetic energy production.