Diverse Surface Signatures of Stratospheric Polar Vortex Anomalies
Details
Serval ID
serval:BIB_497807C0875D
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Diverse Surface Signatures of Stratospheric Polar Vortex Anomalies
Journal
Journal of Geophysical Research: Atmospheres
ISSN
2169-897X
2169-8996
2169-8996
Publication state
Published
Issued date
27/10/2022
Peer-reviewed
Oui
Volume
127
Number
20
Language
english
Abstract
The Arctic stratospheric polar vortex is an important driver of winter weather and climate variability and predictability in North America and Eurasia, with a downward influence that on average projects onto the North Atlantic Oscillation (NAO). While tropospheric circulation anomalies accompanying anomalous vortex states display substantial case-by-case variability, understanding the full diversity of the surface signatures requires larger sample sizes than those available from reanalyses. Here, we first show that a large ensemble of seasonal hindcasts realistically reproduces the observed average surface signatures for weak and strong vortex winters and produces sufficient spread for single ensemble members to be considered as alternative realizations. We then use the ensemble to analyze the diversity of surface signatures during weak and strong vortex winters. Over Eurasia, relatively few weak vortex winters are associated with large-scale cold conditions, suggesting that the strength of the observed cold signature could be inflated
due to insufficient sampling. For both weak and strong vortex winters, the canonical temperature pattern in Eurasia only clearly arises when North Atlantic sea surface temperatures are in phase with the NAO. Over North America, while the main driver of interannual winter temperature variability is the El Niño–Southern Oscillation (ENSO), the stratosphere can modulate ENSO teleconnections, affecting temperature and circulation anomalies over North America and downstream. These findings confirm that anomalous vortex states are associated with a broad spectrum of surface climate anomalies on the seasonal scale, which may not be fully captured by the small observational sample size.
due to insufficient sampling. For both weak and strong vortex winters, the canonical temperature pattern in Eurasia only clearly arises when North Atlantic sea surface temperatures are in phase with the NAO. Over North America, while the main driver of interannual winter temperature variability is the El Niño–Southern Oscillation (ENSO), the stratosphere can modulate ENSO teleconnections, affecting temperature and circulation anomalies over North America and downstream. These findings confirm that anomalous vortex states are associated with a broad spectrum of surface climate anomalies on the seasonal scale, which may not be fully captured by the small observational sample size.
Keywords
ENSO, stratosphere, NAO
Web of science
Open Access
Yes
Create date
05/12/2022 11:55
Last modification date
10/07/2024 6:05