Collaborative Research: The combined influence of sea ice and snow cover on Northern Hemisphere atmospheric climate variability

北极冰雪是气候系统不可分割的一部分。在过去的十年里，它们经历了前所未有的变化。关于其可变性的潜在的、遥远的和更大范围的影响的初步研究往往是不确定的，甚至是相互矛盾的。在最近的一篇评论文章中，这一提议的主要调查人员(PI)假设，海冰和积雪可以结合在一起，迫使大气发生大范围的变化。本项目的重点是分析再分析数据集和有针对性的数值模拟试验的模式输出，以了解将海冰和雪盖变化与大气气候变化联系起来的物理途径。这种变化反过来可能会影响季节性时间尺度上的中纬度天气。了解这些过程预计将改善类似时间尺度的天气预报，从而为能源、农业和再保险等行业带来好处。该项目将通过支持研究生的培训、引导本科生从事科学研究以及开发气候预测短期课程，为科学、技术和经济管理学院的人力资源开发做出贡献。最后，该项目将促进与一家德国研究机构的国际协作。利用全大气社区气候模式(WACCM)进行的预先描述的海冰和雪盖扰动实验将导致对海冰、积雪和大气变率的启动和维持之间的物理路径进行定量评估，特别是在冬季，这是单靠统计分析无法完成的。使用最近才出现的高顶模式来研究海冰和积雪覆盖对半球冬季环流的影响是这一提议的新颖之处。同时，PI将与使用ECHAM6进行类似实验的同事合作。他们将进一步分析再分析大气数据，以检验从模型输出中了解到的关于海冰和积雪在气候变异性中的组合作用的假设。拟议的项目将分析海冰和雪盖异常对大气气候变异性的综合影响。这将增进对与海冰和雪覆盖变化有关的大气反应的了解，并导致对高纬度和低纬度气候之间的联系进行定量评估，并使气候预测得以改进。拟议的研究特别侧重于海冰和积雪在启动和维持高纬度大气变率的主导模式，即环状模式中的综合作用。环状模式的调制被认为是高纬度气候反馈的关键物理机制，也是包括美国、欧洲和亚洲工业中心在内的中纬度地区的主要可变性模式。在本项目中制定的概念框架将在项目结束时应用于业务季节性预报模式。

Arctic snow and ice form an integral part of the climate system. They have undergone unprecedented changes within the past decade. Initial studies on the potential remote and larger scale influences of their variability have often been inconclusive and even contradictory. In a recent review article, the principal investigators (PIs) of this proposal hypothesized that sea ice and snow cover can combine to force large-scale atmospheric variability. This project focuses on analyzing reanalysis datasets and model output from targeted numerical modeling experiments in order to understand the physical pathways linking sea ice and snow cover variability with atmospheric climate variability. This variability may, in turn, influence mid-latitude weather on seasonal time scales. Understanding such processes is anticipated to improve weather prediction on similar time scales, with consequent benefits to the energy, farming, and reinsurance industries, amongst others. The project will contribute to STEM manpower development through providing support for the training of a graduate student, entrainment of undergraduate students into scientific research, and development of a short course of climate prediction. Finally, the project will promote international collaboration with a German research institute.Prescribed sea ice and snow cover perturbation experiments with the Whole Atmosphere Community Climate Model (WACCM) will lead to a quantitative assessment of the physical pathways between sea ice, snow cover and the initiation and maintenance of atmospheric variability, particularly in winter, that cannot be accomplished using statistical analysis alone. The use of a high-top model, which has only recently become available, to study the influence of sea ice and snow cover on the hemispheric winter circulation is novel to this proposal. In parallel, the PIs will collaborate with colleagues running similar experiments with ECHAM6. They will further analyze reanalysis atmospheric data, to test hypotheses about the combined role of sea ice and snow cover in climate variability learned from the model output. The proposed project will analyze the combined impact of sea ice and snow cover anomalies on atmospheric climate variability. This will improve understanding of the atmospheric response associated with changes in sea ice and snow cover, and lead to a quantitative assessment of the links between high-latitude and lower-latitude climates as well as enable improved climate predictions. The proposed research focuses specifically on the combined role of sea ice and snow cover in the initiation and maintenance of the dominant mode of high-latitude atmospheric variability, i.e. the annular mode. Modulation of the annular mode is hypothesized to be a key physical mechanism for climate feedback in high latitudes and is the dominant mode of variability in the mid-latitudes including the industrial centers of the United States, Europe and Asia. The conceptual framework developed in this project will be applied in an operational seasonal forecast model at the end of the project.