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| Titel |
Increasing the Atlantic subtropical jet cools the circum-North Atlantic Region |
| VerfasserIn |
Gerard van der Schrier, Sybren Drijfhout, WIlco Hazeleger, Ludovic Noulin, Geert-Jan van Oldenborgh |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250035615
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| Zusammenfassung |
| Part of a scenario for abrupt climate change over the North Atlantic sector in a General
Circulation Model of intermediate complexity is modelled. Central to this scenario is the
hypothesis that a substantial strengthening of the Atlantic subtropical jet will lead to a
reorganization of the mid-latitude atmospheric circulation in which the Atlantic subtropical
and eddy-driven jets coincide. The subtropical jet over the North Atlantic sector is
increased by calculating optimal model tendency perturbations, using a recently
developed technique. Strengthening of the subtropical jet is achieved by model tendency
perturbations which (1) sharpen the meridional gradient in streamfunction or (2)
force a strong and persistently negative North Atlantic Oscillation pattern in the
upper troposphere. Both approaches lead to similar forcing patterns. It is found that
when the subtropical jet is sufficiently strong, the eddy-driven jet is indeed drawn to
the northern rim of the subtropical jet. This reduces atmospheric meridional heat
transport over the North Atlantic. In the model, a positive feedback is observed; the
southern sea ice-edge extends further south and snowcover over Europe is more
persistent. All factors combined result in an overall cooling of the circum-North Atlantic
region. |
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