报告题目一：Arctic sea-ice loss leads to more frequent strong El Niño events
报告人：刘骥平 中山大学 教授
报告摘要：Arctic sea ice has decreased substantially and is projected to reach a seasonally ice-free state in the coming decades. Little is known whether decreasing Arctic sea ice is capable of influencing the occurrence of strong El Niño, a prominent mode of climate variability with global impacts. Based on time slice coupled model experiments, we show that no significant change in the occurrence of strong El Niño is found in response to moderate Arctic sea-ice loss that is consistent with satellite observations to date. However, as the Arctic becomes seasonally ice-free, the frequency of strong El Niño events increases by more than one third, as defined by gradient-based El Niño indices that remove mean tropical Pacific warming induced by Arctic sea-ice loss. By comparing our time slice experiments with greenhouse warming experiments, we conclude that more than one third of the increase of strong El Niño near the end of the 21st century is associated specifically with Arctic sea-ice loss. Further separation of Arctic sea-ice loss and greenhouse gas forcing only experiments implies that the seasonally ice-free Arctic might play a key role in driving significantly more frequent strong El Niño events.
报告人：杨小怡 厦门大学 教授
报告人简介： 杨小怡，厦门大学海洋与地球学院教授。 2007年毕业于中科院南海海洋研究所，物理海洋学博士；2008-2010年于加拿大环境署气候模式与分析中心（CCCma）从事博士后研究工作，2014-2015美国哥伦比亚大学LDEO访问学者，2019年赴挪威卑尔根大学短期访学。主要研究兴趣为中高纬度大气-海洋动力学，大尺度海-气-冰相互作用，极地气候变化等方向。研究成果聚焦于大气西风急流、南极绕极流的涡流相互作用机制；西边界流动力学和跨洋盆输送；极地海冰变异的动力机制以及北极海冰减退的气候效应等。发表SCI论文30余篇，研究成果为Journal of Climate, Geophysical Research Letters, Cryosphere等国际顶级期刊收录。
报告摘要：After an unprecedented retreat, the total Arctic sea ice cover for the post-2007 period is characterized by low extent and a remarkable increase in annual cycle amplitude. We have identified the leading role of spring Bering sea ice in explaining the changes in the amplitude of the annual cycle of total Arctic sea ice. In particular, these changes are related to the recent occurrence of multiyear variability in spring Bering sea ice extent. This is due to the phase-locking of the NPGO and PDO after about 2007. Furthermore, there emerge notable changes in the sea level pressure and sea surface temperature patterns associated with the NPGO in the recent decade. After 2007, the NPGO is related to a quadrupole of sea level pressure anomalies that is associated with the wind stress curl and Ekman pumping rate anomalies in the Bering deep basin; These account for the change in Bering Sea subsurface variability that contribute to the decadal oscillation of the spring Bering sea ice extent.