The Evolution of Polar Climates: Forcings, Feedbacks, and Coupled Atmosphere-Ocean-Ice Dynamics

极地气候的演变：强迫、反馈和耦合的大气-海洋-冰动力学

• 批准号: RGPIN-2019-07211
• 负责人: Singh, Hansi
• 金额: $ 2.19万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=739363
• 关键词: Evolution; Polar; Climates; Forcings; Feedbacks

The polar regions are among the most vulnerable to anthropogenic climate change, with observed warming over the Arctic nearly triple that over the rest of the globe. This phenomenon of rapid high--latitude climate change, polar amplification, is evident over the Arctic in nearly all climate model simulations, and has been attributed to local radiative feedbacks (associated with both sea ice loss and the stability of the polar atmosphere) and changes in energy convergence by the atmosphere and ocean. This rapid rate of climate change in the polar regions has implications for global sea level, marine ecosystems, and extrapolar atmospheric circulation patterns, with anticipated societal impacts on coastal habitability, fishery productivity, and extreme weather, among others. The polar regions release much more energy to space than what they absorb from the sun, in effect acting as cooling radiator fins for the planet. This functionality, in turn, is made possible by the large--scale transport of extrapolar energy by the atmosphere and oceans into the polar regions. In a changing climate, changes in the cooling efficiency of the polar radiator fins depend on radiative feedbacks and changes in energy transport, which also affect polar and extrapolar climatology. In the proposed research program, I will investigate the evolving relationship between top--of-atmosphere polar energy loss, polar radiative feedbacks, and changing (atmosphere and ocean) energy convergence into the polar regions over a variety of time scales. Using models, observations, and applied mathematical techniques, we focus on the following objectives: 1. To quantify the temporal evolution of polar top--of--atmosphere energy loss with greenhouse gas forcing, and co--evolving contributions from radiative feedbacks and energy transport changes. 2. To understand Bjerknes compensation of atmospheric and oceanic energy transport into the high latitudes by identifying dynamic mechanisms of coupled energy transport adjustment. 3. To assess the relationship between fluctuations in polar top-of-atmosphere energy loss with natural variability and with forced climatic change. 4. To quantify the predictive power of sea ice in determining the polar climate state, top-of--atmosphere energy loss, radiative feedbacks (other than ice--albedo), and energy transport adjustments. 5. To assess the extrapolar impacts of polar climate change through a framework of varying regional forcings, radiative feedbacks, and atmospheric and oceanic energy transport adjustments. This research program will expand upon my prior work polar climate change through a lens of interacting local feedback mechanisms alongside adjustments in large--scale atmosphere--ocean coupled dynamics. More broadly, it will establish a framework for greater understanding and prediction of polar and extrapolar climate change, with particular relevance for climate change impacts, adaptation, and mitigation in the Canadian Arctic.

极地地区是最容易受到人为气候变化影响的地区之一，北极地区观测到的变暖幅度几乎是全球其他地区的三倍。在几乎所有的气候模式模拟中，这种高纬度气候快速变化的现象，即极地放大，在北极上空都很明显，并被归因于当地的辐射反馈（与海冰损失和极地大气的稳定性有关）以及大气和海洋能量汇聚的变化。极地地区的快速气候变化对全球海平面、海洋生态系统和极外大气环流模式都有影响，并对沿海可居住性、渔业生产力和极端天气等产生预期的社会影响。极地向太空释放的能量比它们从太阳吸收的能量要多得多，实际上就像地球的散热片一样。反过来，这种功能是由于大气和海洋向极地地区大规模输送极外能量而成为可能的。在气候变化中，极地散热器翅片冷却效率的变化取决于辐射反馈和能量输运的变化，这些变化也影响极地和极外气候学。在提出的研究计划中，我将研究在不同的时间尺度上，大气顶部的极地能量损失、极地辐射反馈和向极地地区变化的（大气和海洋）能量汇聚之间的演变关系。利用模型、观察和应用数学技术，我们专注于以下目标：量化极地大气顶部能量损失随温室气体强迫的时间演化，以及辐射反馈和能量输运变化的共同演化贡献。2. 通过确定耦合能量输运调整的动力机制，了解高纬度大气和海洋能量输运的Bjerknes补偿。3. 评估极地大气顶部能量损失波动与自然变率和强迫气候变化之间的关系。4. 量化海冰在确定极地气候状态、大气顶部能量损失、辐射反馈（除冰反照率外）和能量输送调整方面的预测能力。5. 通过不同区域强迫、辐射反馈以及大气和海洋能量输送调整的框架评估极地气候变化的极外影响。本研究计划将通过相互作用的局部反馈机制以及大尺度大气-海洋耦合动力学的调整来扩展我之前的极地气候变化工作。更广泛地说，它将建立一个框架，以便更好地了解和预测极地和极外气候变化，特别与加拿大北极地区的气候变化影响、适应和缓解有关。