Polar amplification dominated by local forcing and feedbacks
Polar amplification dominated by local forcing and feedbacks
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DOI：
10.1038/s41558-018-0339-y
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发表时间：
2018-12-01
影响因子：
30.7
通讯作者：
Jin, Fei-Fei
中科院分区：
文献类型：
--
作者：
Stuecker, Malte F.;Bitz, Cecilia M.;Jin, Fei-Fei
地面温度对温室气体强迫的响应表现出极放大变暖的特征模式（1-5），特别是在北方半球。然而，这种极性放大的原因仍然存在争议。一些研究强调了表面反射反馈的重要性（6-8），而另一些研究发现长波反馈的贡献更大（4，9，10），大气和海洋热传输的变化也被认为发挥了作用（11-16）。在这里，我们确定的原因极地放大使用气候模式模拟，其中CO2强迫规定在不同的地理区域，与气候响应的线性和区域强迫复制响应全球强迫。极地放大的程度强烈依赖于CO2强迫的位置。特别是，极地放大被发现占主导地位的强迫在极地地区，特别是通过积极的本地失效率反馈，冰的引力和普朗克反馈发挥辅助作用。极外强迫进一步被证明有利于极地变暖，但鉴于它通过增强向极的热量输送诱导了基本均匀的变暖模式，它对极地放大作用的贡献很小。因此，了解极地放大主要需要更好地了解当地的强迫和反馈，而不是极外的过程。
The surface temperature response to greenhouse gas forcing displays a characteristic pattern of polar-amplified warming(1-5), particularly in the Northern Hemisphere. However, the causes of this polar amplification are still debated. Some studies highlight the importance of surface-albedo feedback(6-8), while others find larger contributions from longwave feedbacks(4,9,10), with changes in atmospheric and oceanic heat transport also thought to play a role(11-16). Here, we determine the causes of polar amplification using climate model simulations in which CO2 forcing is prescribed in distinct geographical regions, with the linear sum of climate responses to regional forcings replicating the response to global forcing. The degree of polar amplification depends strongly on the location of CO2 forcing. In particular, polar amplification is found to be dominated by forcing in the polar regions, specifically through positive local lapse-rate feedback, with ice-albedo and Planck feedbacks playing subsidiary roles. Extra-polar forcing is further shown to be conducive to polar warming, but given that it induces a largely uniform warming pattern through enhanced poleward heat transport, it contributes little to polar amplification. Therefore, understanding polar amplification requires primarily a better insight into local forcing and feedbacks rather than extra-polar processes.