Large-scale Atmospheric Circulation and Multidecadal Variability of the North Atlantic Ocean

大西洋多年代际振荡（AMO）是北大西洋大部分地区海温（SST）同时变冷或变暖的一种变化形式，从暖到冷的振荡周期为60 ~ 70年。 AMO已被证明会影响北美和欧洲的降水，并与巴西东北部和萨赫勒地区的降雨和干旱有关。 AMO被认为与北大西洋的翻转环流有关，因此，较慢的翻转导致AMO的冷阶段，而较快的翻转导致温暖阶段。虽然以前的研究集中在AMO对夏季降水和干旱的影响，本文的工作是讨论AMO对北方半球大气环流的影响以及由此引起的冬季天气和气候影响的可能性。 这里假设的特殊效应是AMO影响北大西洋涛动（NAO），这是一种影响欧洲和北美天气和气候的海平面气压和风的大规模波动。 预期的关系是这样的AMO的暖相有利于NAO的负相，其特征是更曲折的急流和冷空气爆发的发生率增加。 测试这种关系的研究包括对20世纪世纪再分析（20 CR）数据集的分析，其中大气天气和环流场是根据1871年至2010年的地面气压计读数重建的，沿着同一时期的SST记录。 观测分析增加了数值模式模拟，旨在捕捉大气响应强加AMO SST，这些模拟进一步比较的档案耦合气候模式模拟耦合模式相互比较项目版本5（CMIP 5）。 该研究还将考虑AMO间接影响NAO的可能性，因为温暖的SST导致北极冰盖减少，这反过来又影响大气环流。由于NAO对美国和欧洲冬季严酷程度的影响，因此更好地了解AMO对NAO的影响是必要的，特别是考虑到AMO的缓慢变化可能意味着冬季条件的某种程度的可预测性。除了研究成果的社会效益外，这项工作还将通过支持研究生产生更广泛的影响，从而为未来的气候研究提供劳动力。 此外，研究人员还将参加一个名为“气候扫盲赋权和iNquiry（CLEAN）”的外展计划。 该方案的对象是小学和中学的儿童。

AbstractThe Atlantic Multidecadal Oscillation (AMO) is a form of sea surface temperature (SST) variation in which SSTs over a large portion of the North Atlantic simultaneously warm or cool, with oscillations from warm to cold taking place over a period of 60 to 70 years. The AMO has been shown to influence precipitation over North America and Europe, and is linked to rainfall and drought over Northeast Brazil and the Sahel. The AMO is thought to be linked to the overturning circulation of the North Atlantic, so that slower overturning results in the cold phase of the AMO, while faster overturning leads to the warm phase.While previous studies have focused on the impacts of the AMO on precipitation and drought during the summer season, work here addresses the possibility of an AMO influence on Northern Hemisphere atmospheric circulation and consequent weather and climate impacts during the winter. The particular effect hypothesized here is that the AMO influences the North Atlantic Oscillation (NAO), a large-scale fluctuation of sea level pressure and wind which affects the weather and climate of Europe and North America. The expected relationship is such that the warm phase of the AMO favors the negative phase of the NAO, which is characterized by a more meandering jet stream and increased incidence of cold air outbreaks. Research to test this relationship includes analysis of the 20th Century Reanalysis (20CR) dataset, in which atmospheric weather and circulation fields are reconstructed based on surface barometer readings from 1871 to 2010, along with SST records from the same time period. The observational analysis is augmented with numerical model simulations intended to capture the atmospheric response to imposed AMO SSTs, and these simulations are further compared to the archive of coupled climate model simulations prepared for the Coupled Model Intercomparison Project version 5 (CMIP5). The research will also consider the possibility that the AMO affects the NAO indirectly, as warm SSTs lead to reduced Arctic ice cover, which in turn affects atmospheric circulation.A better understanding of the effects of the AMO on the NAO is desirable due to the impact of the NAO on the severity of winters in the US and Europe, particularly given that the slow variation of the AMO could imply some level of predictability for winter conditions. In addition to the societal benefit of the research results, the work will have broader impacts by supporting a graduate student, thereby providing for the future workforce in climate research. In addition, the researchers will participate in an outreach program titled "Climate Literacy Empowerment And iNquiry (CLEAN). The program is targeted at elementary and middle school children.