Can Eurasia Experience a Cold Winter under a Third-Year La Niña in 2022/23?

Abstract

The Northern Hemisphere (NH) often experiences frequent cold air outbreaks and heavy snowfalls during La Niña winters. In 2022, a third-year La Niña event has exceeded both the oceanic and atmospheric thresholds since spring and is predicted to reach its mature phase in December 2022. Under such a significant global climate signal, whether the Eurasian Continent will experience a tough cold winter should not be assumed, despite the direct influence of mid- to high-latitude, large-scale atmospheric circulations upon frequent Eurasian cold extremes, whose teleconnection physically operates by favoring Arctic air invasions into Eurasia as a consequence of the reduction of the meridional background temperature gradient in the NH. In the 2022/23 winter, as indicated by the seasonal predictions from various climate models and statistical approaches developed at the Institute of Atmospheric Physics, abnormal warming will very likely cover most parts of Europe under the control of the North Atlantic Oscillation and the anomalous anticyclone near the Ural Mountains, despite the cooling effects of La Niña. At the same time, the possibility of frequent cold conditions in mid-latitude Asia is also recognized for this upcoming winter, in accordance with the tendency for cold air invasions to be triggered by the synergistic effect of a warm Arctic and a cold tropical Pacific on the hemispheric scale. However, how the future climate will evolve in the 2022/23 winter is still subject to some uncertainty, mostly in terms of unpredictable internal atmospheric variability. Consequently, the status of the mid- to high-latitude atmospheric circulation should be timely updated by medium-term numerical weather forecasts and sub-seasonal-to-seasonal prediction for the necessary date information and early warnings.

摘要

拉尼娜年北半球冬季易经历冷空气频繁爆发和大雪等天气。在2022年, 第三年拉尼娜事件春季后再次达到拉尼娜事件的判定标准, 预计将在2022年12月达到盛期。在拉尼娜事件爆发的气候背景下, 同时考虑中高纬度大尺度大气环流变化的直接影响, 欧亚大陆是否会经历一个冷冬值得探索。本报告利用中科院大气物理研究所发展的多个气候模式的季节预测和多种统计方法的诊断分析得出结果：2022/23年冬季, 在北大西洋涛动和乌拉尔山附近异常反气旋的控制下, 气温异常变暖将很可能覆盖欧洲大部分地区；同时也需要警惕暖北极、冷热带在半球尺度上的协同效应将使得亚洲中纬度地区可能会频繁遭遇寒潮事件。但由于大气内部变率的不可预测性, 2022/23年冬季欧亚大陆气候将如何演变仍存在诸多不确定性。因此, 为获取及时准确的预警信息, 中高纬大气环流的变化应通过中期数值天气预报和次季节-季节气候预测等方式滚动更新。