Characterizing Shallow Cumulus and Its Drivers Over the Tibetan Plateau

Abstract Shallow cumulus (ShCu) influences regional atmospheric circulation and suppresses summer precipitation by modulating surface radiation and energy budgets, yet its macrophysical characteristics and environmental controls remain unclear over the Tibetan Plateau (TP). This study defines ShCu as cumulus with depth ≤2 km and analyzes its properties and environmental drivers using 15 years (2006–2020) of CloudSat and CALIPSO satellite observations, complemented by ERA5 reanalysis and high‐resolution topography. ShCu occurs most frequently in summer and during the daytime, with the highest cloud fractions over the western and southeastern TP. It dominates cumulus across all seasons, accounting for approximately three‐quarters of the cumulus over the TP annually. Among the environmental drivers, near‐surface relative humidity (RH2m) emerges as the primary control, regulating both ShCu occurrence and dominance. Specifically, moderate RH2m levels tend to favor frequent and dominant ShCu by promoting condensation while limiting deep convection, as seen in the western TP year‐round. In contrast, highly moist conditions combined with strong updrafts at 500 hPa in the southeastern TP during summer promote cloud deepening into cumulus congestus, yielding lower ShCu cloud fraction (∼8.8%) and dominance (∼0.62) than in the west (∼14.4%, ∼0.80). Furthermore, ShCu over the TP exhibits a lower average cloud base (∼0.83 km) than in surrounding regions, with the lowest values observed over the western TP during winter and nighttime, closely linked to reduced lifting condensation levels. These findings highlight a distinct ShCu regime over the TP and offer insights for improving its parameterization by incorporating terrain complexity and realistic near‐surface humidity.