Melting icebergs provide nearly half of the total freshwater flux from ice shelves to the ocean, but the availability of accurate, data-constrained melting rate parametrisations limits the correct representation of this process in ocean models. Here, we investigate the melting of a vertical ice face in a warm, salt-stratified environment in a laboratory setting. Observations of the depth-dependent melting rates ${m}$ and boundary layer flow speed $U$ are reported for a range of initially uniform far-field ambient temperatures $T_a$ above ${10}\,^{\circ }{\rm C}$ . Ice scallops are characteristic features observed in all experiments, with the width of the scallops consistent with the theory of double-diffusive layers. The morphology of the scallops changes from symmetric about the scallop centre in the colder experiments to asymmetric in the warmer experiments. Observed melting rates are consistent with a melting rate scaling of the form ${m}\propto U\,\Delta T_a$ proposed by previous work in less extreme parameter regimes, where $\Delta T_a$ is the magnitude of thermal driving between the ambient and ice–fluid interface. Our results indicate that ice scalloping is closely linked to the naturally convecting flow of the ambient fluid. Depth-averaged melting rates depend on the buoyancy frequency in the ambient fluid, and double-diffusive convection promotes a turbulent-flux regime distinct from that explained previously in an unstratified regime. These findings have implications for parametrising melting rates of icebergs and glaciers in numerical models or potential freshwater harvesting operations, and provide insights into the interplay between stratification and ice melting.

中文翻译：

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温暖盐层环境中冰融化的实验室实验

融化的冰山提供了从冰架到海洋的总淡水通量的近一半，但是精确的、受数据约束的融化速率参数化的可用性限制了海洋模型中这一过程的正确表示。在这里，我们研究了实验室环境中温暖、盐层环境中垂直冰面的融化情况。与深度相关的熔化速率的观察 ${m}$ 和边界层流速 $U$ 报告了一系列最初均匀的远场环境温度 $T_a$ 多于 ${10}\,^{\circ }{\rm C}$ 。冰扇贝是所有实验中观察到的特征，扇贝的宽度符合双扩散层理论。扇贝的形态从较冷的实验中关于扇贝中心的对称变化到较热的实验中的不对称。观察到的熔化速率与以下形式的熔化速率比例一致 ${m}\propto U\,\Delta T_a$ 先前的工作在不太极端的参数范围内提出，其中 $\Delta T_a$ 是环境和冰-流体界面之间热驱动的大小。我们的结果表明，冰扇形现象与环境流体的自然对流密切相关。深度平均熔化速率取决于环境流体中的浮力频率，并且双扩散对流促进了与之前在非分层状态中解释的湍流状态不同的湍流状态。这些发现对于数值模型或潜在的淡水收集操作中冰山和冰川融化速率的参数化具有影响，并提供了对分层和冰融化之间相互作用的见解。