Regional Disparities in Hydro-climatic Extremes Across Central Asia: Insights from the Tienshan Mountains

The Tienshan Mountains of Central Asia, a key region in global arid and semi-arid zones, faces highly uneven precipitation distribution due to its unique topography and climate. Precipitation variations significantly affect the region’s ecosystems, agriculture, and hydrological security. While extreme heavy precipitation has been widely studied, research on extreme light precipitation is limited. Additionally, spatial distribution patterns and driving mechanisms of extreme events under varying climatic and geomorphic conditions remain underexplored. This study systematically examines the spatial-temporal trends of extreme hydro-climatic events in the Tienshan Mountains, focusing on both heavy and light precipitation, to provide insights for water resource management and disaster prevention.

The Tienshan Mountains have experienced significant changes in extreme hydro-climatic events since 2000. The frequency anomaly of extreme light precipitation events (R1p) shifted from positive to negative, indicating a marked decline compared to the historical average, while extreme heavy precipitation events (R99p) shifted from negative to positive, reflecting a substantial increase in frequency. The intensity of both events has also risen notably during this period. Spatially, the intensity variations of extreme events show consistent signals across the Tienshan region, while frequency exhibits strong spatial heterogeneity. Around 80°E, extreme heavy precipitation frequency increases eastward and decreases westward. Vertically, mid-altitudes exhibit the most pronounced changes. The frequency of extreme light precipitation declines at 0.471 days/year in mid-altitudes compared to 0.356 days/year at high altitudes. Similarly, extreme heavy precipitation intensity increases at 0.106 mm/year in mid-altitudes, much higher than 0.014 mm/year at high altitudes. These patterns result from the combined effects of Tibetan Plateau thermal dynamics and monsoon-driven moisture transport, creating distinct differences in extreme precipitation between the eastern and western Tienshan. Future studies should explore the interactions between the plateau and atmospheric circulation to improve the prediction and mitigation of extreme events, aiding water resource management and disaster preparedness.