Consistent Intensification of Extreme Heavy and Light Precipitation Events in the Tienshan Mountains, Central Asia

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. 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, focusing on both extreme heavy and light precipitation, to provide insights for water resource management and disaster prevention. A distinct hydrological regime shift has occurred since 2000. The frequency anomaly of extreme light precipitation events (R1p) plunged from positive to negative, indicating a marked decline, whereas extreme heavy precipitation events (R99p) surged, reflecting a substantial increase in frequency. Spatially, a prominent dipole pattern is identified around 80 degrees E, where extreme heavy precipitation frequency increases eastward and decreases westward. Vertically, the mid-altitude zone acts as an amplification center, exhibiting the sharpest intensification of heavy precipitation and the steepest decline in light precipitation frequency. 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.