Quantifying stratospheric biases and identifying their potential sources in subseasonal forecast systems

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State: Public
Version: Final published version
License: CC BY 4.0
Serval ID
serval:BIB_D22C7CF509AB
Type
Article: article from journal or magazin.
Collection
Publications
Institution
Title
Quantifying stratospheric biases and identifying their potential sources in subseasonal forecast systems
Journal
Weather and Climate Dynamics
Author(s)
Lawrence Zachary D., Abalos Marta, Ayarzagüena Blanca, Barriopedro David, Butler Amy H., Calvo Natalia, de la Cámara Alvaro, Charlton-Perez Andrew, Domeisen Daniela I. V., Dunn-Sigouin Etienne, García-Serrano Javier, Garfinkel Chaim I., Hindley Neil P., Jia Liwei, Jucker Martin, Karpechko Alexey Y., Kim Hera, Lang Andrea L., Lee Simon H., Lin Pu, Osman Marisol, Palmeiro Froila M., Perlwitz Judith, Polichtchouk Inna, Richter Jadwiga H., Schwartz Chen, Son Seok-Woo, Statnaia Irina, Taguchi Masakazu, Tyrrell Nicholas L., Wright Corwin J., Wu Rachel W.-Y.
ISSN
2698-4016
Publication state
Published
Issued date
19/08/2022
Peer-reviewed
Oui
Volume
3
Number
3
Pages
977-1001
Language
english
Abstract
The stratosphere can be a source of predictability for surface weather on timescales of several weeks to months. However, the potential predictive skill gained from stratospheric variability can be limited by biases in the representation of stratospheric processes and the coupling of the stratosphere with surface climate in forecast systems. This study provides a first systematic identification of model biases in the stratosphere across a wide range of subseasonal forecast systems.
It is found that many of the forecast systems considered exhibit warm global-mean temperature biases from the lower to middle stratosphere, too strong/cold wintertime polar vortices, and too cold extratropical upper-troposphere/lower-stratosphere regions. Furthermore, tropical stratospheric anomalies associated with the Quasi-Biennial Oscillation tend to decay toward each system's climatology with lead time. In the Northern Hemisphere (NH), most systems do not capture the seasonal cycle of extreme-vortex-event probabilities, with an underestimation of sudden stratospheric warming events and an overestimation of strong vortex events in January. In the Southern Hemisphere (SH), springtime interannual variability in the polar vortex is generally underestimated, but the timing of the final breakdown of the polar vortex often happens too early in many of the prediction systems.
These stratospheric biases tend to be considerably worse in systems with lower model lid heights. In both hemispheres, most systems with low-top atmospheric models also consistently underestimate the upward wave driving that affects the strength of the stratospheric polar vortex. We expect that the biases identified here will help guide model development for subseasonal-to-seasonal forecast systems and further our understanding of the role of the stratosphere in predictive skill in the troposphere.
Keywords
General Earth and Planetary Sciences, General Environmental Science
Open Access
Yes
Funding(s)
Swiss National Science Foundation / PP00P2_170523
Swiss National Science Foundation / PP00P2_198896
Create date
19/01/2023 18:38
Last modification date
10/07/2024 7:05
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