Melting dynamics of freely floating ice in calm waters

Predicting floating ice dynamics remains a challenging problem with implications for Earth's climate. While gigantic icebergs have garnered worldwide attention, small ice bodies have been overlooked, and we still lack their mechanistic models. Aided by a novel real-time tracking, we unravel the transient processes of freely floating ice in calm waters—including the kinematics, phase transition, and surrounding fluid dynamics—that govern melting. Combining the convective Stefan problem and our experimental results, we develop and validate a theoretical model for the melt rate, identifying ice geometry and convective regime as key controls. Furthermore, the ice-driven convective volume flux is found to exceed the meltwater flux by orders of magnitude, underscoring the ecological relevance of floating ice; it not only supplies freshwater but also acts as a destabilizing buoyancy source that redistributes mass macroscopically. Our study provides a foundation for developing mechanistic parameterizations of icebergs and ice floes melting in climate models.

预测漂浮冰体的动力学行为仍是一项极具挑战性的课题，其研究结果与地球气候息息相关。尽管巨型冰山曾广受全球瞩目，但小型冰体却长期被忽视，目前学界仍缺乏针对其的机理模型。借助新型实时追踪技术，我们阐明了静水中自由漂浮冰体的瞬态演化过程——包括控制其融化过程的运动学、相变及周围流体动力学特性。结合对流斯特藩问题（convective Stefan problem）与本团队的实验结果，我们构建并验证了针对融化速率的理论模型，明确了冰体几何形态与对流模式为两大核心控制因子。此外，研究发现冰体驱动的对流体积通量较融水通量高出数个数量级，这进一步凸显了漂浮冰体的生态意义：其不仅可为生态系统提供淡水，还可作为不稳定浮力源，在宏观尺度上实现质量的重新分配。本研究为气候模型中冰山与浮冰融化的机理化参数化方案开发提供了重要基础。