On the anomalous development of the extremely intense positive Arctic Oscillation of the 2019–2020 winter

Numerous extreme climate anomalies were recorded in the northern extratropics in January–March (JFM) 2020, significantly impacting human lives and ecosystems in the affected areas. Those anomalies were caused by an extreme positive Arctic Oscillation (AO) event, with the JFM 2020 AO index of 2.8 bei...

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Bibliographic Details
Published in:Environmental Research Letters
Main Authors: A Juzbašić, V N Kryjov, J B Ahn
Format: Article in Journal/Newspaper
Language:English
Published: IOP Publishing 2021
Subjects:
Arctic Oscillation
climate dynamics
climate extremes
polar vortex
North Eurasia
Environmental technology. Sanitary engineering
TD1-1066
Environmental sciences
GE1-350
Science
Q
Physics
QC1-999
Arctic
Online Access:https://doi.org/10.1088/1748-9326/abe434
https://doaj.org/article/1cf3e1d85f8d4a348303525c05439fa1
Description
Summary:Numerous extreme climate anomalies were recorded in the northern extratropics in January–March (JFM) 2020, significantly impacting human lives and ecosystems in the affected areas. Those anomalies were caused by an extreme positive Arctic Oscillation (AO) event, with the JFM 2020 AO index of 2.8 being the highest on the record. However, all well-established autumn precursors pointed towards the following wintertime AO phase being negative. Indeed, a negative AO phase was developing until late December when a sudden shift to the strong positive AO event occurred in the troposphere. The geopotential anomalies associated with positive AO spread into the lower stratosphere, and were steadily enhancing throughout JFM resulting in an extreme positive AO event. We show that the strong positive AO event was a result of the destructive interference of the anomalous planetary waves with climatological ones, which led to wave flattening and enhancement of the polar vortex.

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