scholarly journals Wave breaking along the stratospheric polar vortex as seen in ERA-40 data

2007 ◽  
Vol 34 (8) ◽  
Author(s):  
John T. Abatzoglou ◽  
Gudrun Magnusdottir
Keyword(s):  
Wave Breaking ◽  
Polar Vortex ◽  
Stratospheric Polar Vortex

Planetary Wave Breaking and Tropospheric Forcing as Seen in the Stratospheric Sudden Warming of 2006

2009 ◽  
Vol 66 (2) ◽  
pp. 495-507 ◽  
Author(s):  
Lawrence Coy ◽  
Stephen Eckermann ◽  
Karl Hoppel
Keyword(s):  
North Atlantic ◽  
Wave Breaking ◽  
Potential Temperature ◽  
Polar Vortex ◽  
Stratospheric Polar Vortex ◽  
Stratospheric Sudden Warming ◽  
Advanced Level ◽  
Earth Observing System ◽  
The North ◽  
Temperature Surface

Abstract The major stratospheric sudden warming (SSW) of January 2006 is examined using meteorological fields from Goddard Earth Observing System version 4 (GEOS-4) analyses and forecast fields from the Navy Operational Global Atmospheric Prediction System–Advanced Level Physics, High Altitude (NOGAPS-ALPHA). The study focuses on the upper tropospheric forcing that led to the major SSW and the vertical structure of the subtropic wave breaking near 10 hPa that moved low tropical values of potential vorticity (PV) to the pole. Results show that an eastward-propagating upper tropospheric ridge over the North Atlantic with its associated cold temperature perturbations (as manifested by high 360-K potential temperature surface perturbations) and large positive local values of meridional heat flux directly forced a change in the stratospheric polar vortex, leading to the stratospheric subtropical wave breaking and warming. Results also show that the anticyclonic development, initiated by the subtropical wave breaking and associated with the poleward advection of the low PV values, occurred over a limited altitude range of approximately 6–10 km. The authors also show that the poleward advection of this localized low-PV anomaly was associated with changes in the Eliassen–Palm (EP) flux from equatorward to poleward, suggesting an important role for Rossby wave reflection in the SSW of January 2006. Similar upper tropospheric forcing and subtropical wave breaking were found to occur prior to the major SSW of January 2003.

scholarly journals Quantifying Asymmetric Wave Breaking and Two-Way Transport

2004 ◽  
Vol 61 (22) ◽  
pp. 2735-2748 ◽  
Author(s):  
Noboru Nakamura
Keyword(s):  
Wave Breaking ◽  
Polar Vortex ◽  
Effective Diffusivity ◽  
The Other ◽  
Stratospheric Polar Vortex ◽  
Air Masses ◽  
Rossby Wave Breaking ◽  
Advection Diffusion Equation ◽  
Extratropical Tropopause ◽  
Asymmetric Wave

Abstract Effective diffusivity calculated from a scalar field that obeys the advection–diffusion equation has proved useful for estimating the permeability of unsteady boundaries of air masses such as the edge of the stratospheric polar vortex and the extratropical tropopause. However, the method does not discriminate the direction of transport—whereas some material crosses the boundary from one side to the other, some material does so in the other direction—yet the extant method concerns only the net transport. In this paper, the diagnostic is extended to allow partitioning of fluxes of mass and tracer into opposing directions. This is accomplished by discriminating the regions of “inward” and “outward” wave breaking with the local curvature of the tracer field. The utility of the new method is demonstrated for nonlinear Kelvin– Helmholtz instability and Rossby wave breaking in the stratosphere using a numerically generated tracer. The method successfully quantifies two-way transport and hence the direction of wave breaking—the predominantly equatorward breaking of Rossby waves in the extratropical middle stratosphere, for example. Isolated episodes of mixing are identified well, particularly by the mass flux that primarily arises from the tracer filaments. Comparison of different transport schemes suggests that the results are reasonably robust under a varying subgrid representation of the model.

scholarly journals Synoptic–Dynamic Climatology of the Aleutian High

2018 ◽  
Vol 75 (4) ◽  
pp. 1271-1283 ◽  
Author(s):  
Stephen J. Colucci ◽  
Thomas S. Ehrmann
Keyword(s):  
Wave Breaking ◽  
Geopotential Height ◽  
Polar Vortex ◽  
Heat Fluxes ◽  
Aleutian Islands ◽  
Height Anomaly ◽  
Reanalysis Dataset ◽  
Stratospheric Polar Vortex ◽  
Geometric Moments ◽  
Almost All

Abstract A climatology of the anticyclone that commonly appears over the Aleutian Islands in the wintertime Northern Hemisphere stratosphere is presented. Applying a geometric moments technique to a reanalysis dataset and updating a previously published definition, 68 Aleutian high (AH) events have been identified during 35 winter (October–March) seasons (1979/80–2013/14), or about 2 events per season. The events lasted an average of approximately 33 days. Thirteen of the 68 AH events each temporally and spatially coincided with tropospheric blocking identified with a wave-breaking definition, while 41 of the AH onsets each coincided with a persistently positive geopotential height anomaly in the troposphere. Also, 41 of the 68 AH events each coincided with or were followed by an objectively defined disturbance (split or displacement) to the stratospheric polar vortex. Finally, 47 of these disturbance events were each preceded by an AH onset, such that in almost all winters (33 out of 35), an early season AH was followed by a later-season polar vortex disturbance (PVD). Potential vorticity (PV) inversion revealed that the geopotential height rises associated with composite AH onset were forced primarily by anticyclonic PV increases in the stratosphere, with the troposphere providing a lesser contribution. Poleward eddy heat fluxes in the stratosphere preceded and especially followed composite AH onset, consistent with the findings that composite AH onset was forced primarily by anticyclonic PV increases in the stratosphere and that many AH onsets were each followed by a PVD onset.

scholarly journals On the role of Rossby wave breaking in the quasi‐biennial modulation of the stratospheric polar vortex during boreal winter

2020 ◽  
Vol 146 (729) ◽  
pp. 1939-1959
Author(s):  
Hua Lu ◽  
Matthew H. Hitchman ◽  
Lesley J. Gray ◽  
James A. Anstey ◽  
Scott M. Osprey
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Polar Vortex ◽  
Boreal Winter ◽  
Stratospheric Polar Vortex ◽  
Rossby Wave Breaking

scholarly journals Intraseasonal Variability of the Zonal-Mean Extratropical Tropopause: The Role of Changes in Polar Vortex Strength and Upper-Troposphere Wave Breaking

2016 ◽  
Vol 73 (3) ◽  
pp. 1383-1399 ◽  
Author(s):  
Jesús Á. Barroso ◽  
Pablo Zurita-Gotor
Keyword(s):  
Time Scales ◽  
Wave Breaking ◽  
Intraseasonal Variability ◽  
Dynamical Evolution ◽  
Polar Vortex ◽  
Principal Component ◽  
Qualitative Behavior ◽  
Stratospheric Polar Vortex ◽  
Anomalous Wave ◽  
The Impact

Abstract A principal component analysis of the Northern Hemisphere extratropical zonal-mean tropopause variability at intraseasonal time scales is presented in this work. Wavy deformations of the tropopause dominate this variability and explain significantly more variance than changes in the extratropical-mean tropopause height. The first mode is well correlated with the zonal index. Analysis of the dynamical evolution of the modes shows that tropopause deformations are caused by anomalous wave breaking at the tropopause level occurring in a preexisting anomalous stratospheric polar vortex. Specifically, an intense (weak) polar vortex is associated with a rising (sinking) of the polar tropopause, while anomalous wave breaking in the midlatitudes produces a dipolar tropopause change that is consistent with the anomalous meridional eddy flux of quasigeostrophic potential vorticity. These two forcings operate on different time scales and can be separated when the data are filtered at high or low frequency. Baroclinic equilibration seems to play a small role in the extratropical internal tropopause variability and the impact of tropospheric and stratospheric dynamics is quantitatively similar. A similar analysis for the Southern Hemisphere extratropics displays the same qualitative behavior.

scholarly journals Impact of Synoptic-Scale Wave Breaking on the NAO and Its Connection with the Stratosphere in ERA-40

2009 ◽  
Vol 22 (20) ◽  
pp. 5464-5480 ◽  
Author(s):  
Torben Kunz ◽  
Klaus Fraedrich ◽  
Frank Lunkeit
Keyword(s):  
North Atlantic ◽  
Wave Breaking ◽  
Large Scale ◽  
Polar Vortex ◽  
Synoptic Scale ◽  
Stratospheric Polar Vortex ◽  
Close Link ◽  
The North ◽  
The North Atlantic ◽  
The Impact

Abstract This observational study investigates the impact of North Atlantic synoptic-scale wave breaking on the North Atlantic Oscillation (NAO) and its connection with the stratosphere in winter, as derived from the 40-yr ECMWF Re-Analysis (ERA-40). Anticyclonic (AB) and cyclonic wave breaking (CB) composites are compiled of the temporal and spatial components of the large-scale circulation using a method for the detection of AB and CB events from daily maps of potential vorticity on an isentropic surface. From this analysis a close link between wave breaking, the NAO, and the stratosphere is found: 1) a positive feedback between the occurrence of AB (CB) events and the positive (negative) phase of the NAO is suggested, whereas wave breaking in general without any reference to AB- or CB-like behavior does not affect the NAO, though it preferably emerges from its positive phase. 2) AB strengthens the North Atlantic eddy-driven jet and acts to separate it from the subtropical jet, while CB weakens the eddy-driven jet and tends to merge both jets. 3) AB (CB) events are associated with a stronger (weaker) lower-stratospheric polar vortex, characterized by the 50-hPa northern annular mode. During persistent weak vortex episodes, significantly more frequent CB than AB events are observed concurrently with a significant negative NAO response up to 55 days after the onset of the stratospheric perturbation. Finally, tropospheric wave breaking is related to nonannular stratospheric variability, suggesting an additional sensitivity of wave breaking and, thus, the NAO to specific distortions of the stratospheric polar vortex, rather than solely its strength.

scholarly journals Isentropic Transport within the Antarctic Polar-Night Vortex: Rossby Wave Breaking Evidence and Lagrangian Structures

2013 ◽  
Vol 70 (9) ◽  
pp. 2982-3001 ◽  
Author(s):  
Alvaro de la Cámara ◽  
Carlos R. Mechoso ◽  
Ana M. Mancho ◽  
Encarna Serrano ◽  
Kayo Ide
Keyword(s):  
Rossby Wave ◽  
Wave Breaking ◽  
Invariant Manifolds ◽  
Chaotic Behavior ◽  
Polar Vortex ◽  
Arc Length ◽  
Polar Night ◽  
Stratospheric Polar Vortex ◽  
Rossby Wave Breaking ◽  
The Antarctic

Abstract The trajectories in the lower stratosphere of isopycnic balloons released from Antarctica by Vorcore and Concordiasi field campaigns during the southern springs of 2005 and 2010 showed events of latitudinal transport inside the stratospheric polar vortex, both away from and toward the poleward flank of the polar-night jet. The present paper applies trajectory-based diagnostic techniques to examine mechanisms at work during such events. Reverse domain-filling calculations of potential vorticity (PV) fields from the ECMWF Interim Re-Analysis (ERA-Interim) dataset during the events show irreversible filamentation of the PV fields in the inner side of the polar-night jet, which is a signature of planetary (Rossby) wave breaking. Balloon motions during the events are fairly consistent with the PV filaments. Events of both large (~15° of arc length) and small (~5° of arc length) balloon displacements from the vortex edge are associated, respectively, with deep and shallow penetration into the core of the elongated PV contours. Additionally, the Lagrangian descriptor M is applied to study the configuration of Lagrangian structures during the events. Breaking Rossby waves inside the vortex lead to the presence of hyperbolic points. The geometric configuration of the invariant manifolds associated with the hyperbolic trajectories helps to understand the apparent chaotic behavior of balloons' motions and to identify and analyze balloon transport events not captured by reverse domain-filling calculations. The Antarctic polar vortex edge is an effective barrier to air parcel crossings. Rossby wave breaking inside the vortex, however, can contribute to tracer mixing inside the vortex and to occasional air crossings of the edge.

Representation of the Scandinavia-Greenland Pattern and its Relationship with the Polar Vortex in S2S Models

2021 ◽  
Author(s):  
Simon Lee ◽  
Andrew Charlton-Perez ◽  
Jason Furtado ◽  
Steven Woolnough
Keyword(s):  
Heat Flux ◽  
Wave Breaking ◽  
Polar Vortex ◽  
Boreal Winter ◽  
Stratospheric Polar Vortex ◽  
Rossby Wave Breaking ◽  
The North ◽  
Eddy Heat Flux ◽  
Vertically Propagating ◽  
The North Atlantic Oscillation

<p>The strength of the stratospheric polar vortex is a key contributor to subseasonal prediction during boreal winter. Anomalously weak polar vortex events can be induced by enhanced vertically propagating Rossby waves from the troposphere, driven by blocking and wave breaking. Here, we analyse a tropospheric pattern—the Scandinavia–Greenland (S–G) pattern—associated with both processes. The S–G pattern is defined as the second empirical orthogonal function (EOF) of mean sea‐level pressure in the northeast Atlantic. The first EOF is a zonal pattern resembling the North Atlantic Oscillation. We show that the S–G pattern is associated with a transient amplification of planetary wavenumber 2 and meridional eddy heat flux, followed by the onset of a persistently weakened polar vortex. We then analyse 10 different models from the S2S database, finding that, while all models represent the structure of the S–G pattern well, some models have a zonal bias with more than the observed variability in their first EOF, and accordingly less in their second EOF. This bias is largest in the models with the lowest resolution, and consistent with biases in blocking and Rossby wave breaking in these models. Skill in predicting the S–G pattern is not high beyond week 2 in any model, in contrast to the zonal pattern. We find that the relationship between the S–G pattern, enhanced eddy heat flux in the stratosphere, and a weakened polar vortex is initially well represented, but decays significantly with lead time in most S2S models. Our results motivate improved representation of the S–G pattern and its stratospheric response at longer lead times for improved subseasonal prediction of the stratospheric polar vortex.</p>

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