Constraining Arctic wave-ice interactions and the sea ice floe-size distribution

1.近几十年来，北冰洋海冰的面积有所减少。海面波在北极地区正变得越来越常见，因为海冰的消失使海洋表面直接暴露在风产生的海浪中。海冰以碎片的形式漂浮在海洋上，它们在海浪的影响下弯曲和破裂。尽管进入海冰的海浪失去了振幅，但由于浮冰破裂成更小的碎片，间隔更广，海浪传播到海冰更深的地方。高度破裂的海冰更容易侧面融化，从而进一步促进波浪的产生和传播、浮冰破裂和海冰撤退。这一奖项的学术价值在于进一步发展了波-冰相互作用理论，并发展了一种模拟海冰、海洋表面波及其相互作用的地球系统模型。观测将为模型的开发提供信息。使用这些模型进展的气候模拟将是有史以来第一次处理海冰和海浪的相互作用。与过去45年的测量结果相比，以前的气候模拟通常模拟的北极海冰下降幅度太小。在模式中加入海浪-冰相互作用有望改进对过去的模拟，更好地估计下个世纪预期的海冰和气候变化，并对海冰对风暴的响应做出更好的预测。由于了解过去和未来气候变化的重要性，这项工作具有更广泛的影响。未来对北极海冰覆盖、变暖、降雪和海平面上升的预测对于决策是必要的。模拟海冰中的北极海浪对于警告社区有关海岸侵蚀和危险的海岸条件也很重要。项目成果将通过在标准科学期刊上发表来传播。该项目的发现将有助于科学团队教授的关于全球变暖、气候和气候变化、冰和气候相互作用以及气候建模的课程的内容。该项目团队将向公众、高中生和其他科学家讲授研究成果。2.北冰洋海冰的减少使北极盆地和亚极海出现更大的开阔水域，使北极地区更多地产生由风引起的海面波浪。此外，更薄、更不集中、更碎裂的海冰使海浪能够更深地传播到海冰中。由于波浪诱导的弯曲运动，海冰边缘附近的海冰浮冰严重破裂。由于海冰在风和洋流应力的驱动下变形，海冰内部的浮冰也会破裂。严重破裂的海冰会促进横向融化，从而进一步加快海冰的消融速度。观测表明，波浪引起的破裂带的宽度因地区和季节而异，延伸到海冰中长达数百公里。海冰的演化以及大气和海洋的近地表热交换取决于浮标及其周围开阔水域的几何分布。浮游体的分布对边缘附近的海冰状态影响最大，那里的海洋热含量往往最大。观察表明，一场大风暴可能会导致严重的浮冰断裂，并将海洋热量向上混合到铅中，从而加速海冰面积的丧失。这一奖项的学术价值在于进一步发展了波浪-冰相互作用理论，并发展了在广泛使用的海冰模型中预测海冰浮团大小分布的方法。对海冰中波浪衰减的改进也将对波浪模型进行改进。将采用模式和观测与资料同化相结合的方法，动态估计参数。对海冰和海浪成分中浮体大小分布的代码改进将以完全耦合的模式纳入共同体地球系统模型。使用这些模式进展的模拟将是有史以来第一次量化动力海冰破裂在耦合气候系统中的作用。新的动力预计将增加北极气候反馈，并提高模式的预测能力。增加的海冰反馈预计将在北极风暴期间加强海冰的流失，北极风暴的东侧吹南风。该模型将允许对海冰如何在气候系统中演化进行新的基础研究。这项工作具有更广泛的影响，因为了解温室气体浓度上升和其他气候强迫导致的过去和未来气候变化的重要性。未来对北极温度、降水、冰块平衡和海平面上升的预测对于决策是必要的。模拟海冰中的北极海浪对于预测海岸侵蚀和危险的海岸条件也很重要。项目成果将通过在标准科学期刊上发表来传播。该项目的发现将有助于科学团队教授的关于全球变暖、气候和气候变化、冰和气候相互作用以及气候建模的课程的内容。该项目团队将向公众、高中生和其他科学家讲授研究成果。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

1. Arctic sea ice has declined in area over recent decades. Ocean surface waves are becoming more common in the Arctic as sea ice loss exposes the ocean surface directly to wind producing waves. Sea ice floats on the ocean in pieces called floes that flex and fracture under the influence of waves. Although waves traveling into the sea ice lose amplitude, waves propagate deeper into sea ice as floes are fractured into smaller pieces and are more widely spaced. Sea ice that is highly fractured is more prone to side melt, therefore further enabling wave production and propagation, floe fracture, and sea ice retreat. The intellectual merit of this award is the furthering of wave-ice interaction theory and developments to an Earth system model that simulates sea ice floes, ocean surface waves and their interactions. Observations will inform the model developments. Climate simulations with these model advances will be the first ever to treat sea ice and wave interactions. Previous climate simulations have generally simulated too little Arctic sea ice decline compared to measurements over the last 45 years. Including wave-ice interactions in the model is expected to improve the simulation of the past, produce a better estimate of expected sea ice and climate change over the next century, and yield better forecasts of the sea ice response to storms.This work has broader impacts due to the importance of understanding past and future climate change. Future projections of Arctic sea ice cover, warming, snowfall, and sea level rise are necessary to inform policy decisions. Simulating Arctic waves in sea ice is also important for warning communities about coastal erosion and hazardous coastal conditions. The project results will be disseminated by publishing in standard scientific journals. The project findings will contribute to the content of courses the science team teaches on global warming, climate and climate change, ice and climate interactions, and climate modeling. The project team will give lectures on research findings to the public, to high-school students, and broadly to other scientists. 2. The decline of Arctic sea ice exposes larger open water areas in the Arctic Basin and subpolar seas, enabling greater production of local wind driven ocean surface waves in the Arctic. In addition, thinner, less concentrated, and more fractured sea ice floes permit waves to propagate deeper into the sea ice pack. Sea ice floe are heavily fractured near the sea ice edge due to wave-induced flexural motion. Floes are also fractured in the interior of the sea ice pack from sea ice deformation driven by wind and current stresses. Heavily fractured sea ice can enhance lateral melt, which further accelerates the rate of sea ice decline. Observations have shown that the width of the wave-induced fracture zone varies by region and seasonal and extends up to a few hundred kilometers into the sea ice. The evolution of the sea ice cover and the near surface heat exchange of atmosphere and ocean depend on the geometric distribution of floes and the open water surrounding them. The distribution of floes has the greatest impact on the sea ice state near the edge, where ocean heat content tends to be greatest. Observations suggest that a single large storm can cause severe floe fracture and mix ocean heat upward into leads, subsequently accelerating the loss of sea ice area. The intellectual merit of this award is the furthering of wave-ice interaction theory and developments to a prognostic floe-size distribution of sea ice in a widely-used sea ice model. Improvements to wave attenuation in sea ice will also be made to a wave model. Objective methods to estimate parameters dynamically while combining models and observations with data assimilation will be employed. Code improvements to the floe-size distribution in sea ice and wave components will be incorporated into the Community Earth System Model, in fully-coupled mode. Simulations with these model advances will be the first ever to quantify the role of dynamical sea ice fracture in the coupled climate system. The new dynamics are expected to increase Arctic climate feedbacks and improve the predictive capability of the model. Increased sea ice feedbacks are expected to strengthen sea ice loss during Arctic storms, where winds are southerly on the eastern flank of storms. The model will permit new fundamental research about how sea ice floes evolve in the climate system.This work has broader impacts due to the importance of understanding past and future climate change from rising greenhouse gas concentrations and other climate forcings. Future projections of Arctic temperature, precipitation, ice mass balance and sea level rise are necessary to inform policy decisions. Simulating Arctic waves in sea ice is also important for predicting coastal erosion and hazardous coastal conditions. The project results will be disseminated by publishing in standard scientific journals. The project findings will contribute to the content of courses that the science team teaches on global warming, climate and climate change, ice and climate interactions, and climate modeling. The project team will give lectures on research findings to the public, to high-school students, and broadly to other scientists.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.