The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variability

The ability of analysing atmospheric dynamics by idealized experiments using a simplified circulation model is illustrated in three related studies. The investigations focus on the organization of localized strom tracks, their impact on low-frequency variability, and on the response to external ther...

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Main Authors: Klaus Fraedrich, Edilbert Kirk, Ute Luksch, Frank Lunkeit
Format: Article
Language:English
Published: Borntraeger 2005-12-01
Series:Meteorologische Zeitschrift
Online Access:http://dx.doi.org/10.1127/0941-2948/2005/0074
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author Klaus Fraedrich
Edilbert Kirk
Ute Luksch
Frank Lunkeit
author_facet Klaus Fraedrich
Edilbert Kirk
Ute Luksch
Frank Lunkeit
author_sort Klaus Fraedrich
collection DOAJ
description The ability of analysing atmospheric dynamics by idealized experiments using a simplified circulation model is illustrated in three related studies. The investigations focus on the organization of localized strom tracks, their impact on low-frequency variability, and on the response to external thermal forcing. A localized storm track in agreement with observations is forced by a heating dipole embedded in a zonally symmetric field if the dipole orientation corresponds to the Northern Hemisphere winter case. The interaction of two storm tracks leads to low-frequency variability. Spatial resonance between a low-frequency large scale retrograde travelling wave and the storm track eddies is identified causing the fluctuations. Teleconnection pattern remarkably similar to the observed North Atlantic Oscillation (NAO) and Pacific North American (PNA) pattern emerge when the distance of the two storm tracks is set to the observed value of about 150°. While the spatial resonance mechanism forces the NAO-like pattern, baroclinic processes are related to the PNA-like teleconnection. Anomalies induced by large scale thermal forcing strongly depend on the background flow. A non-linear response is observed in the model depending on the sign of the forcing and its position relative to the storm track. A baroclinic and an equivalent barotropic component defines the response. In addition, the change of the space-time variability is affected by eddy feedbacks.
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spelling doaj.art-0cf6854beab849caa84a6a0576ad50502024-02-08T08:47:48ZengBorntraegerMeteorologische Zeitschrift0941-29482005-12-0114673574510.1127/0941-2948/2005/007454403The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variabilityKlaus FraedrichEdilbert KirkUte LukschFrank LunkeitThe ability of analysing atmospheric dynamics by idealized experiments using a simplified circulation model is illustrated in three related studies. The investigations focus on the organization of localized strom tracks, their impact on low-frequency variability, and on the response to external thermal forcing. A localized storm track in agreement with observations is forced by a heating dipole embedded in a zonally symmetric field if the dipole orientation corresponds to the Northern Hemisphere winter case. The interaction of two storm tracks leads to low-frequency variability. Spatial resonance between a low-frequency large scale retrograde travelling wave and the storm track eddies is identified causing the fluctuations. Teleconnection pattern remarkably similar to the observed North Atlantic Oscillation (NAO) and Pacific North American (PNA) pattern emerge when the distance of the two storm tracks is set to the observed value of about 150°. While the spatial resonance mechanism forces the NAO-like pattern, baroclinic processes are related to the PNA-like teleconnection. Anomalies induced by large scale thermal forcing strongly depend on the background flow. A non-linear response is observed in the model depending on the sign of the forcing and its position relative to the storm track. A baroclinic and an equivalent barotropic component defines the response. In addition, the change of the space-time variability is affected by eddy feedbacks.http://dx.doi.org/10.1127/0941-2948/2005/0074
spellingShingle Klaus Fraedrich
Edilbert Kirk
Ute Luksch
Frank Lunkeit
The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variability
Meteorologische Zeitschrift
title The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variability
title_full The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variability
title_fullStr The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variability
title_full_unstemmed The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variability
title_short The portable university model of the atmosphere (PUMA): Storm track dynamics and low-frequency variability
title_sort portable university model of the atmosphere puma storm track dynamics and low frequency variability
url http://dx.doi.org/10.1127/0941-2948/2005/0074
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