乌鲁木齐机场多相态降水特征与预报判据浅析

Analysis of Multi-Phase Precipitation Characteristics and Forecasting Criteria at Urumqi Airport

摘要: 乌鲁木齐国际机场位于欧亚大陆腹地，其温带大陆性干旱气候和复杂地形导致多相态降水天气频发。本文基于2022年11月9~10日和2024年4月12~13日两场典型降水过程，综合多源数据，剖析了降水相态转变的动力与热力机制。研究表明，降水相态转变由高空槽移动、冷平流、水汽输送及地形协同作用驱动。温度场对降水相态转变起决定性作用，850 hPa温度变化是关键指标；水汽通量散度变化与相态转变密切相关，低层水汽辐合减弱和中层辐散增强是重要信号。动力条件分析表明，低层强上升运动和辐合是降雨的关键条件，中层辐合减弱和上升运动减小是雨转雨夹雪的特征，低层辐合与中层辐散同时存在时可能预示冰粒天气。本研究为乌鲁木齐机场降水相态预报提供了动力与热力判据，建议重点监测低层散度极值区、中层垂直速度梯度及温度变化趋势，并结合0℃层高度动态调整阈值。研究结果旨在为提高乌鲁木齐机场降水相态预报准确率、保障航空飞行安全提供有力的理论依据与技术支持。

Abstract: Located in the heart of the Eurasian continent, Urumqi International Airport experiences frequent multi-phase precipitation events due to its temperate continental arid climate and complex topography. This study investigates the dynamic and thermodynamic mechanisms driving precipitation phase transitions through two typical precipitation events occurring on November 9~10, 2022 and April 12~13, 2024, utilizing multi-source data. The results demonstrate that precipitation phase transitions are driven by the combined effects of upper-level trough movement, cold advection, moisture transport, and topographic influences. The temperature field plays a decisive role in phase transitions, with 850 hPa temperature variations serving as a key indicator. Changes in water vapor flux divergence show close correlation with phase transitions, where weakened low-level moisture convergence and enhanced mid-level divergence emerge as significant signals. Dynamic analysis reveals that strong low-level upward motion and convergence are critical for rainfall formation, while reduced mid-level convergence and diminished vertical motion characterize the rain-to-sleet transition. The coexistence of low-level convergence and mid-level divergence may indicate impending ice pellet weather. This study establishes dynamic and thermodynamic criteria for precipitation phase forecasting at Urumqi Airport, recommending focused monitoring of extremum zones in low-level divergence, vertical velocity gradients at mid-levels, and temperature trends, combined with dynamic adjustment of thresholds based on 0˚C level height variations. These findings provide theoretical foundation and technical support for improving precipitation phase prediction accuracy and ensuring aviation safety at Urumqi International Airport.