The Key Role of Mixed-Phase and Ice-Phase Processes on the Seasonal Shifts in Drop Size Distribution on the Southeastern Tibetan Plateau

Abstract

This study explores the microphysical characteristics of precipitation on the southeastern Tibetan Plateau (SETP), with a focus on the seasonal variations in drop size distribution (DSD) during distinct monsoon phases. By analyzing long-term observations from a high-altitude region, we uncover a significant differentiation in raindrop concentrations: small raindrops peak during the monsoon phase due to enhanced warm-cloud processes, minimal evaporation rates, and vigorous moisture deposition from sustained humid airflow. Conversely, the premonsoon phase is marked by a higher concentration of large raindrops, primarily driven by strong aggregation and vigorous convective activity. Our results reveal that mixed-phase processes dominate the precipitation microphysics in this region with substantial implications for understanding the underlying mechanisms that govern precipitation variability in high-altitude environments. The interplay between atmospheric dynamics and microphysical processes is crucial in shaping the DSD, highlighting the importance of considering both factors in precipitation modeling. This research not only provides novel insights into the complex interactions between microphysical processes and meteorological conditions but also emphasizes the necessity for enhanced precipitation forecasting models, particularly in regions characterized by complex terrain. These findings offer a foundation for future studies aimed at addressing the impacts of climate change on precipitation patterns and water resource management in the Tibetan Plateau and similar high-altitude regions.