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| Titel |
The Influence of Stratospheric Vortex Displacements and Splits on Surface Climate |
| VerfasserIn |
Dann Mitchell, Lesley Gray, James Anstey, Mark Baldwin, Andrew Charlton-Perez |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250087391
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| Publikation (Nr.) |
 EGU/EGU2014-1435.pdf |
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| Zusammenfassung |
| A strong link exists between stratospheric variability and anomalous weather patterns at the
Earth’s surface. Specifically, during extreme variability of the Arctic polar vortex termed a
“weak vortex event”, anomalies can descend from the upper stratosphere to the surface on
timescales of weeks. Subsequently the outbreak of cold-air events have been noted in high
Northern Latitudes, as well as a quadrapole pattern in surface temperature over the Atlantic
and western European sectors and it is currently not understood why certain events descend
to the surface while others do not. In this study we compare a new classification technique of
weak vortex events, based on the distribution of potential vorticity, with that of an existing
technique and demonstrate that the subdivision of such events into vortex displacements
and vortex splits has important implications for tropospheric weather patterns on
weekly-monthly timescales. Using reanalysis data we find that vortex splitting events are
correlated with surface weather and lead to positive temperature anomalies over eastern
North-America of more than 1.5K, and negative anomalies over Eurasia of up to -3K.
Associated with this is an increase in high-latitude blocking in both the Atlantic and
Pacific sectors and a decrease in European blocking. The corresponding signals
are weaker during displacement events, although ultimately they are shown to be
related to cold-air outbreaks over North America. Owing to the predictability and
importance of stratosphere-troposphere coupling for medium-range weather forecasts, our
findings suggest the need for forecasting systems to correctly identify the type of
stratospheric variability, otherwise surface responses cannot be accurately reproduced. |
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