Warm Greenland during the last interglacial: the role of regional changes in sea ice cover
Warm Greenland during the last interglacial: the role of regional changes in sea ice cover
复制标题
末次间冰期期间格陵兰岛温暖：海冰覆盖区域变化的作用
DOI：
10.5194/cp-12-2011-2016
复制
发表时间：
2016
影响因子：
4.3
通讯作者：
T. Stocker
中科院分区：
文献类型：
--
作者：
N. Merz;A. Born;C. Raible;T. Stocker
抽象的。最后一次间冰期，也被称为Eemian，其特点是高纬度地区的温度比现在高。这是暗示了各种Eemian代理记录以及气候模型模拟，虽然模型大多低估了相对于代理变暖。Eemian表面气温（SAT）在北方半球热带外的模拟进一步显示不同的气候模型之间的差异很大，它已被假设，该模型的传播与Eemian海冰覆盖的不同表示。在这里，我们使用社区气候系统模型（CCSM 3和CCSM 4）的第3和第4版来强调海冰和海面温度变化对Eemian气候的关键作用，特别是在北大西洋部分和格陵兰岛。海冰覆盖的大幅减少导致大气变暖加剧，因此与Eemian代理记录更一致。理想化的下边界条件的敏感性实验表明，格陵兰岛的变暖主要是由于在北欧海洋海冰退缩。相比之下，拉布拉多海的海冰变化对当地的影响有限。这两个区域海冰覆盖的变化通过异常的地表能量通量传递到上覆大气。北欧海洋海冰退缩导致的大规模变暖主要是由异常热平流而不是辐射或凝结过程来解释的。此外，海冰扰动导致水文循环的变化。因此，我们的研究结果意味着格陵兰冰芯的温度和积雪记录是敏感的海冰变化在北欧海域，但不敏感的海冰变化在拉布拉多海。此外，模拟表明，Eemian海冰覆盖的不确定性导致NEEM冰芯站点Eemian变暖1.6 °C。基于NEEM δ15N记录估计的Eemian比现在高5 °C的变暖可以通过CCSM 4模式重建，用于北欧海海冰大量退缩和格陵兰冰盖减少的情景。
Abstract. The last interglacial, also known as the Eemian, is characterized by warmer than present conditions at high latitudes. This is implied by various Eemian proxy records as well as by climate model simulations, though the models mostly underestimate the warming with respect to proxies. Simulations of Eemian surface air temperatures (SAT) in the Northern Hemisphere extratropics further show large variations between different climate models, and it has been hypothesized that this model spread relates to diverse representations of the Eemian sea ice cover. Here we use versions 3 and 4 of the Community Climate System Model (CCSM3 and CCSM4) to highlight the crucial role of sea ice and sea surface temperatures changes for the Eemian climate, in particular in the North Atlantic sector and in Greenland. A substantial reduction in sea ice cover results in an amplified atmospheric warming and thus a better agreement with Eemian proxy records. Sensitivity experiments with idealized lower boundary conditions reveal that warming over Greenland is mostly due to a sea ice retreat in the Nordic Seas. In contrast, sea ice changes in the Labrador Sea have a limited local impact. Changes in sea ice cover in either region are transferred to the overlying atmosphere through anomalous surface energy fluxes. The large-scale spread of the warming resulting from a Nordic Seas sea ice retreat is mostly explained by anomalous heat advection rather than by radiation or condensation processes. In addition, the sea ice perturbations lead to changes in the hydrological cycle. Our results consequently imply that both temperature and snow accumulation records from Greenland ice cores are sensitive to sea ice changes in the Nordic Seas but insensitive to sea ice changes in the Labrador Sea. Moreover, the simulations suggest that the uncertainty in the Eemian sea ice cover accounts for 1.6 °C of the Eemian warming at the NEEM ice core site. The estimated Eemian warming of 5 °C above present day based on the NEEM δ15N record can be reconstructed by the CCSM4 model for the scenario of a substantial sea ice retreat in the Nordic Seas combined with a reduced Greenland ice sheet.
影响因子：
5.2
作者：
X. Zhang;M. Prange;U. Merkel;M. Schulz
通讯作者：
X. Zhang;M. Prange;U. Merkel;M. Schulz