Collaborative Research: Improving the Prediction of Sea Ice through Targeted Study of Poorly Parameterized Sea Ice Processes at MOSAiC and Responsive Model Development

气候模式预估未来北极海冰损失率及其气候影响存在很大的不确定性。在多年代际时间尺度上，这种不确定性主要是由于模式内反馈过程强度的差异。对于北极系统，地表反射的热和光（反照率）的变化主导了反馈过程，地表热平衡的偏离最为显著。然而，模式对许多与地表反照率演化有关的过程采用相对粗糙的表示。为了改进模型预测，我们需要通过相关观测的收集和分析来增强参数化。考虑到正在发生的巨大变化，以及尽快规划和适应变化的迫切需要，更好的北极预测尤为重要。本项目将通过气候模式实验与野外测量相结合的方式，改进气候模式中海冰覆盖和地表热光反射（反照率反馈）的表征。利用群落地球系统模式（CESM）进行敏感性研究，将评估反照率相关参数化不确定性的相对重要性。这些研究将为冰雪、海冰和太阳辐射观测提供信息，这些观测是北极气候研究多学科漂流观测站（MOSAiC）野外活动的一部分。然后，测量将推动CESM内的过程理解和参数化开发。改进后的CESM将进行实验，以确定升级后的反照率反馈表征对地球系统预测的影响。研究的重点将是季节性冰系统中太阳能的分配和命运，雪的性质在控制海冰质量平衡和辐射收支中的作用，以及影响冰-海洋能量交换和冰质量和面积变化的过程。这些领域的过程理解是缺乏的，模型参数化是粗糙的，不确定性对模型预测有很大的影响。通过将模拟和观测工作相结合，将加强对北极太阳能分布和海冰质量收支控制的基本过程认识。将这些知识纳入改进的模式过程表示将加强预测能力，并允许对反照率反馈在预估北极变化中的作用有更深入的了解。模型的发展将被纳入广泛使用的洛斯阿拉莫斯社区冰模型（CICE），并通过CESM和CICE的标准版本免费提供。这将改进气候模型和可操作的海冰预报系统，具有广泛的社会影响。早期职业极地研究人员将大量参与该项目，包括本科生，研究生和博士后学者参与实地和建模活动的机会。为期一年的海冰漂移实验也为学生和公众提供了一个捕捉想象力和兴奋的机会。教育推广工作将包括建立一个由国内和国际参与者组成的中学科学课程网络。活动将包括课堂参观、动手测量活动、数据分析和假设检验。还将通过与当地科学博物馆和教育中心的互动进行进一步的推广。

Climate models project large uncertainty in the rate of future Arctic sea ice loss and its climate impacts. On multi-decadal timescales, this uncertainty is largely due to differences in the strength of feedback processes within the models. For the Arctic system, changes in surface reflection of heat and light (albedo) dominate the feedback process with the most significant departures in the surface heat balance. However, models employ relatively crude representations of many processes that are relevant to surface albedo evolution. To improve model predictions, we need enhanced parameterizations that are informed by the collection and analysis of relevant observations. Better Arctic predictions are particularly critical given the large changes underway and the urgent need to plan for and adapt to changes soon. This project will improve the representation of the sea ice cover and the surface reflection of heat and light (albedo feedback) in climate models through the integration of climate model experiments and field measurements. Sensitivity studies with the Community Earth System Model (CESM) will be used to assess the relative importance of albedo-related parameterization uncertainties. These studies will inform the snow, sea ice, and solar radiation observations conducted as part of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) field campaign. Measurements will then fuel process understanding and parameterization development within CESM. Experiments with the improved CESM will then be performed to determine the effects of upgraded albedo feedback characterization for Earth system predictions. The focus will be on partitioning and fate of solar energy in a seasonal ice system, the role of snow properties in controlling the sea ice mass balance and radiation budget, and processes affecting ice-ocean energy exchange and ice mass and area changes. These are areas for which process understanding is lacking, model parameterizations are crude, and uncertainties have large effects on model projections. By integrating modeling and observational work, the basic process understanding of controls on Arctic solar energy distribution and sea ice mass budgets will be enhanced. The incorporation of this knowledge in improved model process representation will strengthen prediction capabilities and allow for a deeper understanding of the role of the albedo feedback in projected Arctic change. Model developments will be incorporated into the widely-used Los Alamos Community Ice Model (CICE) and made freely available through standard releases of CESM and CICE. This will improve both climate model and operational sea ice forecasting systems with wide-ranging societal implications. Early career polar researchers will be heavily involved in this project, including opportunities for undergraduates, graduate students and post-doctoral scholars to be involved in both field and modeling activities. A year-long sea ice drift experiment also provides an opportunity to capture the imagination and excitement of students and the public. Educational outreach efforts will include developing a network of middle school science classes with national and international participants. Activities will include classroom visits, hands-on measurement activities, data analysis and hypothesis testing. Additional outreach will occur through interactions with local science museums and educational centers.