Keel, Tom;
(2025)
Shifting jet streams in a changing climate.
Doctoral thesis (Ph.D), UCL (University College London).
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Abstract
Changes to atmospheric circulation were recognised as one of the major indicators of large-scale climate change in the latest IPCC assessment report. Despite this, it has been notably difficult to ascertain trends in circulation patterns, partially due to the chaotic nature of the atmosphere. Jet streams are a key feature of the atmospheric circulation, and evidence from climate modelling suggests that they will move polewards in both hemispheres into the 21st century. This could significantly impact the weather patterns over which they exert influence. However, two outstanding issues remain in quantifying changes in the jet and their link to weather. The first issue is that there is little consensus between studies about how the characteristics of jet streams have changed. The latest IPCC report assessed observed changes in the jet streams to have low to medium confidence, especially in the Northern Hemisphere. However, the uncertainty involved in identifying and characterising jet streams is often overlooked as a contributing factor. The second issue is that the exact linkage between the features of the jet streams and surface conditions is not well established, as similar shifts in the jet stream can create divergent surface conditions. This thesis focuses on how different approaches for representing jet streams in the literature have hindered the consensus around their behaviour and representation in models. A new software tool has been created to compute jet stream metrics in a consistent way. Using this tool, a poleward shift in the North Pacific jet has been found over the past few decades, which is robust irrespective of metric or dataset. This poleward trend continues in projections but is subject to model uncertainty. This thesis also demonstrates the benefits of considering jet stream features to explain extreme cold events over North America.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | Shifting jet streams in a changing climate |
| Open access status: | An open access version is available from UCL Discovery |
| Language: | English |
| Additional information: | Copyright © The Author 2025. Original content in this thesis is licensed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) Licence (https://creativecommons.org/licenses/by-nc/4.0/). Any third-party copyright material present remains the property of its respective owner(s) and is licensed under its existing terms. Access may initially be restricted at the author’s request. |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL SLASH UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10204250 |
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