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

1.近几十年来，北极海冰面积有所减少。海洋表面波浪在北极变得越来越常见，因为海冰的损失使海洋表面直接暴露于风产生的波浪。海冰漂浮在海洋上，在波浪的影响下会弯曲和断裂。虽然波浪进入海冰时会失去振幅，但随着浮冰破碎成更小的碎片，波浪会传播到海冰的更深处。高度断裂的海冰更容易发生侧融，因此进一步使波浪产生和传播、浮冰断裂和海冰退缩成为可能。该奖项的智力价值是进一步推进了波冰相互作用理论，并发展了一个模拟海冰、海洋表面波及其相互作用的地球系统模型。观测结果将为模型的开发提供信息。利用这些模型的进展进行的气候模拟将是有史以来第一次处理海冰和波浪相互作用。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太少。在模式中包括波浪-冰相互作用预计将改进对过去的模拟，对下一个世纪的预期海冰和气候变化作出更好的估计，并对海冰对风暴的反应作出更好的预测，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。对北极海冰覆盖、变暖、降雪和海平面上升的未来预测对于政策决策是必要的。在海冰中模拟北极波浪对于警告社区海岸侵蚀和危险的海岸状况也很重要。项目成果将通过在标准科学期刊上发表来传播。该项目的研究结果将有助于科学团队教授全球变暖，气候和气候变化，冰和气候相互作用以及气候建模的课程内容。该项目小组将向公众、高中生和其他科学家广泛介绍研究成果。2.北极海冰的减少暴露了北极盆地和副极地海洋中更大的开放水域，使得北极地区由风驱动的海洋表面波浪产生更多。此外，更薄，更少集中，更破碎的海冰浮冰允许波浪传播到更深的海冰包。由于波浪引起的弯曲运动，海冰边缘附近的浮冰严重断裂。浮冰也在海冰内部破裂，这是由于风和海流应力导致海冰变形。严重断裂的海冰可以促进横向融化，从而进一步加速海冰的下降速度。观测表明，波浪引起的断裂带的宽度因地区和季节而异，并延伸到海冰中数百公里。海冰覆盖的演变以及大气和海洋近地表热交换取决于浮冰的几何分布及其周围的开放水域。浮冰的分布对靠近边缘的海冰状态影响最大，那里的海洋热含量往往最大。观测表明，一次大风暴就能造成严重的浮冰断裂，并将海洋热量向上混合成冰，从而加速海冰面积的丧失。该奖项的学术价值是进一步推进了波冰相互作用理论，并在广泛使用的海冰模型中发展了海冰的预测浮冰尺寸分布。还将对波浪模型进行海冰中波浪衰减的改进。将采用客观方法动态估计参数，同时将模式和观测与数据同化相结合。海冰和波浪组成部分中浮冰大小分布的代码改进将以完全耦合模式纳入社区地球系统模型。模拟这些模式的进步将是有史以来第一次量化的作用，动力海冰断裂的耦合气候系统。新的动态预计将增加北极气候反馈，提高模型的预测能力。预计海冰反馈的增加将加剧北极风暴期间的海冰损失，因为风暴东侧的风是南风。该模型将允许对海冰如何在气候系统中演变进行新的基础研究。由于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，这项工作具有更广泛的影响。对北极温度、降水、冰量平衡和海平面上升的未来预测对于政策决定是必要的。模拟海冰中的北极波浪对于预测海岸侵蚀和危险的海岸状况也很重要。项目成果将通过在标准科学期刊上发表来传播。该项目的研究结果将有助于科学团队教授全球变暖，气候和气候变化，冰和气候相互作用以及气候建模的课程内容。项目组将向公众、高中生以及其他科学家就研究成果进行演讲。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值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.