Arctic Sea Ice Growth in Response to Synoptic- and Large-Scale Atmospheric Forcing from CMIP5 Models
Arctic Sea Ice Growth in Response to Synoptic- and Large-Scale Atmospheric Forcing from CMIP5 Models
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DOI：
10.1175/jcli-d-19-0326.1
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发表时间：
2020-07
影响因子：
4.9
通讯作者：
L. Cai;Vladimir A Alexeev;J. Walsh
中科院分区：
文献类型：
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作者：
L. Cai;Vladimir A Alexeev;J. Walsh
我们探索冬季北极海冰增长的响应，以强气旋和大尺度环流模式的日常使用地球系统模型输出的耦合模式相互比较项目（CMIP 5）的第5阶段。组合指标排名方法选择了三个成功再现冬季北极偶极（AD）模式的CMIP 5模型。一个气旋识别方法，选择在北大西洋的两个次区域的强气旋，检查它们对海冰生长的不同影响。海冰增长率（SGR）的总变化分为动力和热力大气强迫驱动的。三种模式再现了向下长波辐射异常，一般匹配热力SGR异常，在响应强气旋和大尺度环流模式。对于大尺度环流模式，负的AD在抑制SGR方面的影响面积和强度都超过了正的北极涛动。尽管在空间分布上存在分歧，但三个CMIP5模型一致认为动态SGR的响应弱于热力学SGR。随着北极变暖，海冰变薄导致更多的冰生产和更小的厚度的空间异质性，抑制SGR响应的动力强迫。较高的温度增加了海冰的比热，从而抑制了SGR对热力强迫的响应。这样，大气强迫预计在未来气候中对日SGR变化的贡献较小。
We explore the response of wintertime Arctic sea ice growth to strong cyclones and to large-scale circulation patterns on the daily scale using Earth system model output in phase 5 of the Coupled Model Intercomparison Project (CMIP5). A combined metrics ranking method selects three CMIP5 models that are successful in reproducing the wintertime Arctic dipole (AD) pattern. A cyclone identification method is applied to select strong cyclones in two subregions in the North Atlantic to examine their different impacts on sea ice growth. The total change of sea ice growth rate (SGR) is split into those respectively driven by the dynamic and thermodynamic atmospheric forcing. Three models reproduce the downward longwave radiation anomalies that generally match thermodynamic SGR anomalies in response to both strong cyclones and large-scale circulation patterns. For large-scale circulation patterns, the negative AD outweighs the positive Arctic Oscillation in thermodynamically inhibiting SGR in both impact area and magnitude. Despite the disagreement on the spatial distribution, the three CMIP5 models agree on the weaker response of dynamic SGR than thermodynamic SGR. As the Arctic warms, the thinner sea ice results in more ice production and smaller spatial heterogeneity of thickness, dampening the SGR response to the dynamic forcing. The higher temperature increases the specific heat of sea ice, thus dampening the SGR response to the thermodynamic forcing. In this way, the atmospheric forcing is projected to contribute less to change daily SGR in the future climate.