Coherent Turbulence Signatures Preceding Warm Rain Events From Collocated Cloud Radar and Wind Profiler Observations Across China

Abstract

Warm rain is plagued by a longstanding droplet growth bottleneck, one that turbulence may alleviate by enhancing droplet coalescence in the late condensation phase. Nevertheless, empirical observational support from multiple sites remains scarce. Here, we combine collocated nationwide millimeter cloud radars, radar wind profilers, Himawari‐8/9 satellite cloud‐top temperature retrievals, and surface gauges to compile 819 warm rain events over China during the warm seasons of 2024–2025. During the 2 hr preceding rainfall, reflectivity and turbulent dissipation rate (ε) increase simultaneously within mid‐to‐low cloud layers. Cloud reflectivity is found to positively correlate with log10ε ${\log }_{10}\,\varepsilon $ throughout the pre‐rain period, with maximum spatial coherence and statistically significant correlation coefficients occurring 48–18 min before rainfall onset. This pre‐onset window provides multi‐site observational evidence for coordinated turbulence–reflectivity evolution, consistent with the conceptual framework that lower troposphere turbulence modulates warm rain microphysical processes and advances rainfall onset.