Jet speed variability obscures Euro‐Atlantic regime structure
Euro‐Atlantic regimes are typically identified using either the latitude of the North Atlantic jet or clustering algorithms in the phase space of 500‐hPa geopotential (Z500). However, while robust trimodality is visibly apparent in jet latitude indices, Z500 clusters require highly sensitive signifi...
Published in: | Geophysical Research Letters |
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Main Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
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American Geophysical Union
2020
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Online Access: | https://doi.org/10.1029/2020gl087907 https://ora.ox.ac.uk/objects/uuid:4cc6f783-4c8b-4040-a42b-d7cec320f9a4 |
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ftuloxford:oai:ora.ox.ac.uk:uuid:4cc6f783-4c8b-4040-a42b-d7cec320f9a4 2024-10-06T13:51:07+00:00 Jet speed variability obscures Euro‐Atlantic regime structure Dorrington, J Strommen, KJ 2020-08-05 https://doi.org/10.1029/2020gl087907 https://ora.ox.ac.uk/objects/uuid:4cc6f783-4c8b-4040-a42b-d7cec320f9a4 eng eng American Geophysical Union doi:10.1029/2020gl087907 https://ora.ox.ac.uk/objects/uuid:4cc6f783-4c8b-4040-a42b-d7cec320f9a4 https://doi.org/10.1029/2020gl087907 info:eu-repo/semantics/openAccess CC Attribution (CC BY) Journal article 2020 ftuloxford https://doi.org/10.1029/2020gl087907 2024-09-06T07:47:33Z Euro‐Atlantic regimes are typically identified using either the latitude of the North Atlantic jet or clustering algorithms in the phase space of 500‐hPa geopotential (Z500). However, while robust trimodality is visibly apparent in jet latitude indices, Z500 clusters require highly sensitive significance tests to distinguish them from autocorrelated noise. This leads to considerable decadal variability in regime patterns, confounding many potential applications. A clear‐cut choice of the optimal number of regimes is also hard to justify. We argue that the jet speed, a near‐Gaussian distribution projecting strongly onto the Z500 field, is the source of these difficulties. Once its influence is removed, the phase space becomes visibly non‐Gaussian, and clustering algorithms easily recover three regimes, closely corresponding to the jet latitude modes. Further analysis supports the existence of two additional blocking regimes, corresponding to a tilted and split jet. All five regimes are approximately stationary across the twentieth century. Article in Journal/Newspaper North Atlantic ORA - Oxford University Research Archive Geophysical Research Letters 47 15 |
institution |
Open Polar |
collection |
ORA - Oxford University Research Archive |
op_collection_id |
ftuloxford |
language |
English |
description |
Euro‐Atlantic regimes are typically identified using either the latitude of the North Atlantic jet or clustering algorithms in the phase space of 500‐hPa geopotential (Z500). However, while robust trimodality is visibly apparent in jet latitude indices, Z500 clusters require highly sensitive significance tests to distinguish them from autocorrelated noise. This leads to considerable decadal variability in regime patterns, confounding many potential applications. A clear‐cut choice of the optimal number of regimes is also hard to justify. We argue that the jet speed, a near‐Gaussian distribution projecting strongly onto the Z500 field, is the source of these difficulties. Once its influence is removed, the phase space becomes visibly non‐Gaussian, and clustering algorithms easily recover three regimes, closely corresponding to the jet latitude modes. Further analysis supports the existence of two additional blocking regimes, corresponding to a tilted and split jet. All five regimes are approximately stationary across the twentieth century. |
format |
Article in Journal/Newspaper |
author |
Dorrington, J Strommen, KJ |
spellingShingle |
Dorrington, J Strommen, KJ Jet speed variability obscures Euro‐Atlantic regime structure |
author_facet |
Dorrington, J Strommen, KJ |
author_sort |
Dorrington, J |
title |
Jet speed variability obscures Euro‐Atlantic regime structure |
title_short |
Jet speed variability obscures Euro‐Atlantic regime structure |
title_full |
Jet speed variability obscures Euro‐Atlantic regime structure |
title_fullStr |
Jet speed variability obscures Euro‐Atlantic regime structure |
title_full_unstemmed |
Jet speed variability obscures Euro‐Atlantic regime structure |
title_sort |
jet speed variability obscures euro‐atlantic regime structure |
publisher |
American Geophysical Union |
publishDate |
2020 |
url |
https://doi.org/10.1029/2020gl087907 https://ora.ox.ac.uk/objects/uuid:4cc6f783-4c8b-4040-a42b-d7cec320f9a4 |
genre |
North Atlantic |
genre_facet |
North Atlantic |
op_relation |
doi:10.1029/2020gl087907 https://ora.ox.ac.uk/objects/uuid:4cc6f783-4c8b-4040-a42b-d7cec320f9a4 https://doi.org/10.1029/2020gl087907 |
op_rights |
info:eu-repo/semantics/openAccess CC Attribution (CC BY) |
op_doi |
https://doi.org/10.1029/2020gl087907 |
container_title |
Geophysical Research Letters |
container_volume |
47 |
container_issue |
15 |
_version_ |
1812179290575339520 |