How Tropical Pacific Surface Cooling Contributed to Accelerated Sea Ice Melt from 2007 to 2012 as Ice Is Thinned by Anthropogenic Forcing
How Tropical Pacific Surface Cooling Contributed to Accelerated Sea Ice Melt from 2007 to 2012 as Ice Is Thinned by Anthropogenic Forcing
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DOI：
10.1175/jcli-d-18-0783.1
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发表时间：
2019-12-01
影响因子：
4.9
通讯作者：
Lu, Jian
中科院分区：
文献类型：
--
作者：
Baxter, Ian;Ding, Qinghua;Lu, Jian
在过去的40年里，9月份的北极海冰最小值有所下降。2007年至2012年期间，加速融化导致了2007年和2012年创纪录的最小值。这里，观测和模式证据表明，自2000年代以来夏季海冰的变化反映了北极大气环流的年代际变率掩盖了持续的人为强迫融化。这种变化部分是由热带太平洋中东部的海表温度（SST）变化通过传播到北极的罗斯比波串引起的遥相关驱动的[本文称为太平洋-北极遥相关（PARC）]，它代表了连接极地和低纬度地区的主要内部模态。从2007年到2012年，这种模式加速了变暖和北极海冰的减少，随后几年减少速度减慢，导致过去11年出现了减缓的现象。一个起搏器模式模拟，其中我们指定在热带东太平洋观测到的海温，证明了PARC模态的物理可信机制。然而，基于模型的PARC机制相当弱，仅部分解释了2007年至2012年观测到的海冰损失加速。我们还探讨了在长（1800年）CESM工业化前模拟中与极端融化期相关的大尺度环流模式的特征。这些结果进一步支持了源自热带太平洋的远端海温强迫可以激发北极显著的暖期。然而，需要进一步的研究来确定模式在再现观测到的以太平洋冷-北极暖连接为特征的PARC模态方面存在局限性的原因。
Over the past 40 years, the Arctic sea ice minimum in September has declined. The period between 2007 and 2012 showed accelerated melt contributed to the record minima of 2007 and 2012. Here, observational and model evidence shows that the changes in summer sea ice since the 2000s reflect a continuous anthropogenically forced melting masked by interdecadal variability of Arctic atmospheric circulation. This variation is partially driven by teleconnections originating from sea surface temperature (SST) changes in the east-central tropical Pacific via a Rossby wave train propagating into the Arctic [herein referred to as the Pacific-Arctic teleconnection (PARC)], which represents the leading internal mode connecting the pole to lower latitudes. This mode has contributed to accelerated warming and Arctic sea ice loss from 2007 to 2012, followed by slower declines in recent years, resulting in the appearance of a slowdown over the past 11 years. A pacemaker model simulation, in which we specify observed SST in the tropical eastern Pacific, demonstrates a physically plausible mechanism for the PARC mode. However, the model-based PARC mechanism is considerably weaker and only partially accounts for the observed acceleration of sea ice loss from 2007 to 2012. We also explore features of large-scale circulation patterns associated with extreme melting periods in a long (1800 yr) CESM preindustrial simulation. These results further support that remote SST forcing originating from the tropical Pacific can excite significant warm episodes in the Arctic. However, further research is needed to identify the reasons for model limitations in reproducing the observed PARC mode featuring a cold Pacific-warm Arctic connection.