Spatial and Temporal Variability of Cloud Water Content and Precipitation Efficiency in the Tienshan Mountains

Abstract The Tienshan Mountains, central Asia’s critical “water tower,” play a pivotal role in regional water supply and ecological stability. Recent warming has significantly altered precipitation and cloud water dynamics, affecting runoff and water storage patterns. This study investigates the spatiotemporal characteristics of total cloud water (TCW) and precipitation efficiency (PE) over the past four decades (1979–2023) using ERA5 and GPCP data. Results reveal distinct spatial patterns: TCW peaks in the northern and western Tienshan while reaching minima in southern Kyrgyzstan and Xinjiang’s Bayanbulak and Hami regions. Vertical profiles show TCW maxima near 500 hPa, with summer concentrations (700–200 hPa) exceeding other seasons, where snow water dominates cloud composition. Precipitation decreases northwest to southeast, contrasting with PE’s west-high–east-low distribution. Notably, increasing TCW trends in the eastern/central Tienshan alleviate historical aridity, while declines in northern/western regions exacerbate drought risks. The eastern Tienshan exhibits stable TCW levels with summer growth potential, suggesting promising opportunities for cloud water resource utilization, particularly for mitigating water stress in this vulnerable ecosystem.