近日，北京大学张庆红教授团队在研究追踪冰雹垂直生长轨迹的同位素分析中取得新进展。相关论文于2024年9月10日发表于国际顶尖学术期刊《大气科学进展》杂志上。

由于无法直接追踪冰雹在云中的生长轨迹，这阻碍了人们对其潜在生长机制的理解。本研究通过检测不同冰雹壳的稳定同位素特征作为代用物，研究了冰雹的垂直生长轨迹，从而获得了冰雹生长过程中的环境温度。用空腔衰荡光谱仪测量了9次冰雹中27颗冰雹的2H和18O组成。

研究通过比较由绝热模式导出的云中冷凝水的同位素组成，与在冰雹中测量到的同位素组成，获得了垂直生长轨迹。虽然研究人员主要在-10至-30℃温度层观察到冰雹的生长，但不同冰雹的胚形成高度和随后的生长轨迹存在显著差异。胚胎形成的温度范围很广(-8.7°C至-33.4°C)；其中4个的起源温度在-15℃以上，16个的起源温度在-20℃以下，表明冰核分别由生物蛋白和矿物质组成。

观测到的27个冰雹中，3个表现出最小的垂直运动，16个表现出单调的上升或下降轨迹，其余8个表现出上下交替的轨迹；只有一个在上下漂移过程中经历了“循环”。轨迹分析表明，同一场风暴形成的大小相似的冰雹往往在相似的高度形成，而直径大于25毫米的冰雹则至少有一段时间呈上升趋势。由同位素分析得出的垂直轨迹被雷达水文气象观测所证实。

附：英文原文

Title: Isotopic Analysis for Tracing Vertical Growth Trajectories of Hailstones

Author: Xiangyu Lin, Haifan Zhang, Xiaofei Li, Qinghong Zhang, Andrew Heymsfield, Kai Bi, Chan-Pang Ng, Chong Wu, Dianli Gong

Issue&Volume: 2024-09-10

Abstract: The growth trajectory of hailstones within clouds has remained elusive due to inability to trace them directly, impeding comprehension of the underlying growth mechanisms. This study investigated hailstone vertical growth trajectories by detecting the stable isotope signatures of different hailstone shells as proxies, which allowed us to capture the ambient temperature during hailstone growth. The 2H and 18O compositions were measured in 27 hailstones from nine hailstorms using a cavity ring-down spectrometer. The vertical growth trajectories were obtained by comparing the isotopic compositions of water condensate in clouds, derived from the Adiabatic Model, with those measured in hailstones. Although hailstone growth was primarily observed in the -10°C to -30°C temperature layer, the embryo formation height and subsequent growth trajectories significantly varied among hailstones. Embryos formed over a wide range of temperatures (-8.7°C to -33.4°C); four originated at temperatures above -15°C and 16 originated at temperatures below -20°C, suggesting ice nuclei composed of bioprotein and mineral dust, respectively. Among the 27 measured hailstones, three exhibited minimal vertical movement, sixteen exhibited a monotonic rise or fall, and the remaining eight exhibited alternating up-down trajectories; only one experienced “recycling” during up-down drifting. Trajectory analysis revealed that similar-sized hailstones from a single storm tended to form at similar heights, whereas those larger than 25 mm in diameter exhibited at least one period of upward growth. Vertical trajectories derived from isotopic analysis were corroborated by radar hydrometeor observations.

DOI: 10.1007/s00376-024-4211-x

Source: http://www.iapjournals.ac.cn/aas/en/article/doi/10.1007/s00376-024-4211-xviewType=HTML