Climatic Change Impacts and Risks in the Anthropocene (C-CIA), Institute for Environmental Sciences, University of Geneva, Geneva, Switzerland.
Dendrolab.ch, Department of Earth Sciences, University of Geneva, Geneva, Switzerland.
Ann N Y Acad Sci. 2019 Jan;1436(1):206-216. doi: 10.1111/nyas.13911. Epub 2018 Jul 2.
In this study, we analyze the linkage between atmosphere and ocean modes and winter flood variability over the 20th century based on long-term flow-discharge series, historical archives, and tree-ring records of past floods in the North Atlantic Basin (NAB). The most extreme winter floods occurred in 1936 and had strong impacts on either side of the Atlantic. We hypothesize that the joint effects of sea surface temperatures (SSTs) over the Atlantic and Pacific Oceans and the Arctic Oscillation (AO), which is closely related to the North Atlantic Oscillation, play a significant role when describing flood variability in North America and Europe since 1900. Statistical modeling supports the assumption that the response of flood anomalies over the NAB to AO phases is subsidiary of SST phases. Besides, we shed light on the extraordinarily winter flood of 1936 that was characterized by very high SSTs over both the Atlantic and Pacific (>98th percentile) and very low, negative values of AO (<1st percentile). This outstanding winter flood episode was most likely characterized by stratospheric polar vortex anomalies, which can usually be linked to an increased probability of storms in western and southwestern Europe and increased snowfall events in eastern North America. By assessing the flood anomalies over the NAB as a coupled AO and SST function, one could further the understanding of such large-scale events and presumably improve anticipation of future extreme flood occurrences.
在这项研究中，我们基于长期的流量排放序列、历史档案和北大西洋流域（NAB）过去洪水的树木年轮记录，分析了大气和海洋模式之间的联系以及 20 世纪冬季洪水的变化。最极端的冬季洪水发生在 1936 年，对大西洋两岸都产生了强烈的影响。我们假设，大西洋和太平洋的海表温度（SSTs）以及与北大西洋涛动密切相关的北极涛动（AO）的共同作用，在描述自 1900 年以来北美和欧洲的洪水变化时具有重要意义。统计模型支持这样的假设，即 NAB 洪水异常对 AO 相位的响应是 SST 相位的次要因素。此外，我们还研究了 1936 年异常冬季洪水的情况，该年大西洋和太平洋的 SST 非常高（超过第 98 百分位），而 AO 的值非常低，为负（低于第 1 百分位）。这种异常的冬季洪水事件很可能是平流层极涡异常引起的，通常与欧洲西部和西南部风暴概率增加以及北美东部降雪事件增加有关。通过将 NAB 的洪水异常评估为 AO 和 SST 的耦合函数，人们可以进一步了解此类大规模事件，并可能提高对未来极端洪水事件的预测能力。
