Collaborative Research: Polar Amplification and High-Latitude Climate Sensitivity in Global Climate Models

气候模式通常显示出地表空气温度随温室气体水平增加而增加的两极放大效应。然而，在20世纪观测到的极地放大的证据是模糊的，导致一些人质疑模型的敏感性。此外，模式之间的高纬度敏感性的范围很广，这表明在负责向极放大的物理过程方面仍然存在分歧。透过这项合作研究计划，研究员将进行一项研究，以提高对极向放大的理解。一些候选的反馈过程，包括冰的反馈，可能会影响高纬度气候敏感性，他们将评估其相对影响。他们的方法是用一个气候模式进行敏感性研究，并比较在三个不同的气候模式中实施相同的海冰组成模式时的模式敏感性。他们还将在一个由15名成员组成的20世纪世纪模拟集合中分析极地气候变化，以探索内部变化或外部强迫的可能原因。他们还将比较模拟和观察到的极性放大。 他们计划在大部分研究中使用社区气候系统模型（CCSM），并将CCSM的极地气候敏感性与另外两个模型的敏感性进行比较，一个来自地球物理流体动力学实验室（GFDL），另一个来自哈德利气候预测和研究中心。这三个模型一起表现出广泛的极地放大和全球气候敏感性。他们计划与这些机构的合作者一起，通过将CCSM的海冰部分实施到其他两个模型中，评估海冰物理学在极地气候敏感性中的作用。然后，他们将评估模型之间的敏感性范围在多大程度上取决于海冰物理学。发展模拟中心之间的伙伴关系是更好地理解和模拟极地气候敏感性的必要步骤。这项合作汇集了华盛顿大学、洛杉矶的加州大学、国家大气研究中心、GFDL和哈德利中心的科学家。该项目还将支持研究生，鼓励他们参观建模中心，参加会议和研讨会。此外，该项目的结果将影响PI教授的课程。最后，模拟将立即提供给CCSM极地气候工作组的所有成员，该工作组对任何人开放。

Climate models generally exhibit a poleward amplification of the surface air temperature increase that occurs in response to increased greenhouse gas levels. However, observational evidence of polar amplification during the 20th century is ambiguous, leading some to question the models' sensitivity. Furthermore, the wide range of high latitude sensitivity among models suggests disagreements remain regarding the physical processes responsible for poleward amplification. By means of this collaborative research project, the PIs will conduct a study to improve understanding of poleward amplication. A number of candidate feedback processes, including ice-albedo feedback, might affect high latitude climate sensitivity, and they will evaluate their relative impacts. Their approach is to perform sensitivity studies with one climate model, and to compare model sensitivity when the same sea ice component model is implemented in three different climate models. They will also analyze polar climate variations in a 15-member ensemble of 20th century simulations to explore possible attribution to internal variability or external forcing. They will also compare simulated and observed polar amplification. They plan to use the Community Climate System Model (CCSM) for much of the study, and compare the polar climate sensitivity of CCSM to the sensitivities of two other models, one from the Geophysical Fluid Dynamics Laboratory (GFDL) and the other from the Hadley Centre for Climate Prediction and Research. Together, these three models exhibit a wide range of polar amplification and global climate sensitivity. With their collaborators at these institutions, they plan to evaluate the role of sea ice physics in polar climate sensitivity by implementing the sea ice component from CCSM into the other two models. Then they will evaluate to what extent the range of sensitivity among the models depends on sea ice physics.Developing partnerships among modeling centers is a necessary step towards better understanding and simulation of polar climate sensitivity. This collaboration brings together scientists at the University of Washington, the University of California at Los Angeles, the National Center for Atmospheric Research, GFDL, and the Hadley Centre. The project will also support graduate students, who will be encouraged to visit modeling centers and attend conferences and workshops. In addition, results from this project will influence courses taught by the PIs. Finally, the simulations will be available immediately to all members of the CCSM Polar Climate Working Group, which is open to anyone.