Arctic and Pacific Ocean Conditions Were Favorable for Cold Extremes over Eurasia and North America during Winter 2020/21

• DOI: 10.1175/bams-d-21-0264.1
• Publication Date: 2022-07-15T18:38:42Z
• Authors: Ruonan Zhang; James A. Screen; Renhe Zhang
• Keywords: Extreme Cold; Cold wave; Middle latitudes; Siberian High

Abstract A sequence of extreme cold events occurred across Eurasia and North America during winter 2020/21. Here, we explore the causes associated mechanisms for extremely temperatures using both observations large-ensemble simulations. Experiments were conducted with observed ocean surface boundary conditions prescribed globally, regionally to discern specific influence Arctic, tropical Pacific, Pacific drivers. Increased likelihood daily extremes in mid-December mid-January are found Eurasian midlatitudes response reduced Arctic sea ice. Tropical temperature anomalies, more specifically La Niña pattern, increased probability over high-latitude early January February. Both ice western late We conclude that a combination ice, Niña, sudden stratospheric warming 2021 factors February wave caused huge societal disruptions Texas southern Great Plains. Although magnitude simulated relatively small when compared Ocean 2020/21 days as or colder than by approximately 17%–43%.