Sunglint imprints of steady subcloud cells anchoring intermittent trade cumulus

Abstract How can seemingly random, shallow trade-wind clouds be predicted and their climate impact better evaluated? These clouds cool the planet but are hard to represent because they appear sparse and short-lived. We show that, beneath this apparent disorder, the flow is organized as a dense lattice of steady convective cells that tile the subcloud layer. These cells form the dynamic backbone of the cloud field, with their updraft walls serving as persistent launch points for cloud plumes. Spaceborne ocean-sunglint observations reveal a matching 1-2 km cellular texture beneath sparse cloud cover, consistent with the subcloud convective cells’ morphology. Together, the modeled dynamics and sunglint fingerprint reframe trade cumulus as organized from below, suggesting a physics-based route to reduce climate-model uncertainty.