Contributions to Polar Amplification in CMIP5 and CMIP6 Models
Contributions to Polar Amplification in CMIP5 and CMIP6 Models
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DOI：
10.3389/feart.2021.710036
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发表时间：
2021-08-20
影响因子：
2.9
通讯作者：
Donohoe, A.
中科院分区：
文献类型：
--
作者：
Hahn, L. C.;Armour, K. C.;Donohoe, A.
作为了解极地气候变化的基本驱动因素的一步，我们评估了与CMIP5相比，耦合模式相互比较项目第6阶段（CMIP6）对极地变暖及其季节和半球不对称性的贡献。CMIP6模型广泛地捕捉到了近几十年来以地表和冬季为主的北极变暖模式，这种模式的速度超过了热带和南极变暖。对于CMIP5和CMIP6，CO2翻两番的实验表明，失效率和表面反射反馈贡献最强的变暖在北极比热带或南极。的相对强度的极地表面的反馈反馈的失误率反馈相比，是敏感的辐射内核的选择，和反馈的反馈贡献最大的模型间传播在两极变暖。通过分别计算潮湿和干燥的大气热量输送，我们发现，增加向极地的水分输送是北极放大的另一个重要驱动因素，预计南极变暖的最大贡献者。季节性的海洋热储存和冬季放大的温度反馈对北极冬季升温峰值和南极冬季升温峰值较弱的贡献最大。与CMIP5相比，CMIP6中更强的极地变暖来自两极更大的表面负反馈，加上北极的负云反馈和南极向极地的水分输送增加。然而，归一化的全球平均地表变暖产生了类似程度的北极放大和只有轻微增加南极放大CMIP6相比CMIP5。
As a step towards understanding the fundamental drivers of polar climate change, we evaluate contributions to polar warming and its seasonal and hemispheric asymmetries in Coupled Model Intercomparison Project phase 6 (CMIP6) as compared with CMIP5. CMIP6 models broadly capture the observed pattern of surface- and winter-dominated Arctic warming that has outpaced both tropical and Antarctic warming in recent decades. For both CMIP5 and CMIP6, CO2 quadrupling experiments reveal that the lapse-rate and surface albedo feedbacks contribute most to stronger warming in the Arctic than the tropics or Antarctic. The relative strength of the polar surface albedo feedback in comparison to the lapse-rate feedback is sensitive to the choice of radiative kernel, and the albedo feedback contributes most to intermodel spread in polar warming at both poles. By separately calculating moist and dry atmospheric heat transport, we show that increased poleward moisture transport is another important driver of Arctic amplification and the largest contributor to projected Antarctic warming. Seasonal ocean heat storage and winter-amplified temperature feedbacks contribute most to the winter peak in warming in the Arctic and a weaker winter peak in the Antarctic. In comparison with CMIP5, stronger polar warming in CMIP6 results from a larger surface albedo feedback at both poles, combined with less-negative cloud feedbacks in the Arctic and increased poleward moisture transport in the Antarctic. However, normalizing by the global-mean surface warming yields a similar degree of Arctic amplification and only slightly increased Antarctic amplification in CMIP6 compared to CMIP5.