Differences in the sub-seasonal predictability of extreme stratospheric events

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Version: Final published version
License: CC BY 4.0
Serval ID
serval:BIB_C9D0DBC86EAD
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Differences in the sub-seasonal predictability of extreme stratospheric events
Journal
Weather and Climate Dynamics
Author(s)
Wu Rachel Wai-Ying, Wu Zheng, Domeisen Daniela I.V.
ISSN
2698-4016
Publication state
Published
Issued date
15/07/2022
Peer-reviewed
Oui
Volume
3
Number
3
Pages
755-776
Language
english
Abstract
Extreme stratospheric events such as sudden stratospheric warming (SSW) and strong vortex events can have downward impacts on surface weather that can last for several weeks to months. Hence, successful predictions of these stratospheric events can be beneficial for extended-range weather prediction. However, the predictability of extreme stratospheric events is most often limited to around 2 weeks or less. The predictability strongly differs within events of the same type and also between event types. The reasons for the observed differences in the predictability, however, are not resolved. We extend the analysis of the predictability of stratospheric extreme events to include wind deceleration and acceleration events, with SSW and strong vortex events as subsets, to conduct a systematic comparison of sub-seasonal predictability between events in the European Centre for Medium-Range Weather Forecasts (ECMWF) prediction system. Events of stronger magnitude are found to be less predictable than weaker events for both wind deceleration and acceleration events, with both types of events showing a close to linear dependence of predictability on event magnitude. There are, however, deviations from this linear behaviour for very strong magnitude events. The difficulties of the prediction system in predicting extremely strong anomalies can be traced to a poor predictability of extreme wave activity fluxes in the lower stratosphere, which impacts the prediction of deceleration events and, interestingly, also acceleration events. Our study suggests that improvements in the understanding of the wave amplification that is associated with extremely strong wave activity fluxes and accurately representing these processes in the model are expected to enhance the predictability of stratospheric extreme events and, by extension, their impacts on surface weather and climate.
Open Access
Yes
Funding(s)
Swiss National Science Foundation / PP00P2_170523
Swiss National Science Foundation / PP00P2_198896
Create date
19/01/2023 19:32
Last modification date
10/07/2024 7:05
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