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Stratospheric downward wave reflection events modulate North American weather regimes and cold spells

Messori, Gabriele and Kretschmer, Marlene and Lee, Simon H. and Wendt, Vivien (2022) Stratospheric downward wave reflection events modulate North American weather regimes and cold spells. Weather and Climate Dynamics, 3 (4), pp. 1215-1236. Copernicus Publications. doi: 10.5194/wcd-3-1215-2022. ISSN 2698-4016.

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Official URL: https://wcd.copernicus.org/articles/3/1215/2022/


The Arctic stratospheric polar vortex is an important driver of mid-latitude winter cold spells. One proposed coupling mechanism between the stratospheric polar vortex and the troposphere is upward-propagating planetary waves being reflected downward by the polar vortex. However, while the wave reflection mechanism is well-documented, its role in favouring cold spells is still under-explored. Here, we analyse such stratospheric wave reflections and their impact on the tropospheric circulation and surface temperatures over North America in winter. We present a physically interpretable regional stratospheric wave reflection detection metric and identify the tropospheric circulation anomalies associated with prolonged periods of wave reflection, which we term reflection events. In particular, we characterise the tropospheric anomalies through the lens of North American weather regimes. Stratospheric reflection events show a systematic evolution from a Pacific Trough regime – associated on average with positive temperature anomalies and a nearcomplete absence of anomalously cold temperatures in North America – to an Alaskan Ridge regime, which favours low temperatures over much of the continent. The most striking feature of the stratospheric reflection events is thus a rapid, continental-scale decrease in temperatures. These emerge as continental-scale cold spells by the end of the reflection events. Stratospheric reflection events are thus highly relevant in a tropospheric predictability perspective.

Item URL in elib:https://elib.dlr.de/189730/
Document Type:Article
Title:Stratospheric downward wave reflection events modulate North American weather regimes and cold spells
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Messori, GabrieleUppsala University, Swedenhttps://orcid.org/0000-0002-2032-5211UNSPECIFIED
Kretschmer, MarleneDepartment of Meteorology, University of Reading, Reading, UKhttps://orcid.org/0000-0002-2756-9526UNSPECIFIED
Lee, Simon H.Department of Applied Physics and Applied Mathematics, Columbia Universityhttps://orcid.org/0000-0003-0986-0093UNSPECIFIED
Wendt, VivienUNSPECIFIEDhttps://orcid.org/0000-0003-1806-4507UNSPECIFIED
Date:4 November 2022
Journal or Publication Title:Weather and Climate Dynamics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:Yes
In ISI Web of Science:Yes
Page Range:pp. 1215-1236
Publisher:Copernicus Publications
Keywords:Wave reflection, stratosphere, weather regimes, north american cold spell
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Earth Observation
DLR - Research area:Raumfahrt
DLR - Program:R EO - Earth Observation
DLR - Research theme (Project):R - Middle Atmosphere
Location: Neustrelitz
Institutes and Institutions:Institute for Solar-Terrestrial Physics > Solar-Terrestrial Coupling Processes
Deposited By: Wendt, Dr. Vivien
Deposited On:05 Dec 2022 11:30
Last Modified:19 Dec 2023 04:13

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