Simulations of the February 1979 Stratospheric Sudden Warming: Model Comparisons and Three-Dimensional Evolution

Manney, G. L.; Farrara, John D.; Mechoso, Carlos R.

doi:10.1175/1520-0493(1994)122<1115:sotfss>2.0.co;2

Cited by 36 publications

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“…These authors have identified the baroclinic zones as intimate players in the development and evolution of stratospheric warmings. Our observations and the associated Q-vector analysis indicate a region of subsidence on the east side of the polar low, near the baroclinic zone, and convergence westward of the region relating well with the vertical velocity description around baroclinic zones modeled by Fairlie et al [1990] and Manney et al [1994].…”

Section: Analysis and Discussionsupporting

confidence: 85%

Observations of wintertime arctic mesosphere cooling associated with stratosphere baroclinic zones

Thayer¹,

Livingston²

2008

Geophysical Research Letters

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A regional wintertime mesosphere cooling of 30–40 K is observed over the Sondrestrom facility near Kangerlussuaq, Greenland (67.0°N, 309.1°E) during multiple weeks in December 2000 where temperatures from the ground to 90 km were uniquely observed. The negative excursions in mesosphere temperature were observed during times when no thermal changes are observed below 10 hPa (∼30 km), but strong temperature changes are observed above this pressure surface. These thermal features are associated with middle atmosphere disturbances that may occur prior to, or independently of, major stratospheric warmings. They are regionally confined, deviate significantly from ambient conditions, and are likely caused by adiabatic cooling/heating due to strong vertical velocities. We propose that these types of mesosphere cooling events are related to stratospheric baroclinic zones and a Q‐vector analysis of stratospheric geopotential and temperature fields can be used to help identify and describe regional occurrences of significant cooling in the mesosphere.

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Section: Analysis and Discussionsupporting

confidence: 85%

Observations of wintertime arctic mesosphere cooling associated with stratosphere baroclinic zones

Thayer¹,

Livingston²

2008

Geophysical Research Letters

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“…The application of the nonlinear theory to vortex displacement SSWs, which have some complicating features due to their baroclinic vertical structure (e.g., Manney et al 1999;Matthewman et al 2009), is the subject of Part II (Esler and Matthewman 2011).…”

Section: Discussionmentioning

confidence: 99%

“…During a vortex displacement SSW, the polar vortex is displaced from the pole, with the magnitude of the displacement increasing rapidly with altitude (e.g., Manney et al 1999;Matthewman et al 2009), indicating that vortex displacement SSWs have a strongly baroclinic structure. During a vortex split SSW, by contrast, the polar vortex splits almost simultaneously with height (e.g., Manney et al 1994;Matthewman et al 2009); that is, a vortex split SSW has a predominantly barotropic structure. A further feature of vortex split SSWs, as Matthewman et al (2009) have concluded from a study of the 14 observed events during , is that the orientation of the vortex split is approximately parallel to the 608E-1208W meridian (i.e., almost all of the events take place at a more or less fixed orientation to the earth's surface).…”

Section: Introductionmentioning

confidence: 99%

Stratospheric Sudden Warmings as Self-Tuning Resonances. Part I: Vortex Splitting Events

Esler

Matthewman

2011

Journal of the Atmospheric Sciences

105

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The fundamental dynamics of ''vortex splitting'' stratospheric sudden warmings (SSWs), which are known to be predominantly barotropic in nature, are reexamined using an idealized single-layer f-plane model of the polar vortex. The aim is to elucidate the conditions under which a stationary topographic forcing causes the model vortex to split, and to express the splitting condition as a function of the model parameters determining the topography and circulation.For a specified topographic forcing profile the model behavior is governed by two nondimensional parameters: the topographic forcing height M and a surf-zone potential vorticity parameter V. For relatively low M, vortex splits similar to observed SSWs occur only for a narrow range of V values. Further, a bifurcation in parameter space is observed: a small change in V (or M) beyond a critical value can lead to an abrupt transition between a state with low-amplitude vortex Rossby waves and a sudden vortex split. The model behavior can be fully understood using two nonlinear analytical reductions: the Kida model of elliptical vortex motion in a uniform strain flow and a forced nonlinear oscillator equation. The abrupt transition in behavior is a feature of both reductions and corresponds to the onset of a nonlinear (self-tuning) resonance. The results add an important new aspect to the ''resonant excitation'' theory of SSWs. Under this paradigm, it is not necessary to invoke an anomalous tropospheric planetary wave source, or unusually favorable conditions for upward wave propagation, in order to explain the occurrence of SSWs. 1 The present study casts doubt on the accuracy of quasi-linear wave-mean models such as that used by Smith, as it is shown explicitly in section 4d that the interaction of weakly nonlinear vortex Rossby waves with their second harmonic is equally important as their interaction with the zonal mean flow.

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“…The vortex is clearly split by September 26, but only at upper levels, while below ∼26 km it appears to have recovered its circular shape. This ‘partial’ split is a distinguishing feature of the 2002 event, and is distinct from the vortex behavior observed for most Northern Hemisphere events [ Manney et al , 2005], during which the vortex is observed to split near‐simultaneously over its entire altitude range [e.g., Manney et al , 1994].…”

Section: Introductionmentioning

confidence: 94%

The Antarctic stratospheric sudden warming of 2002: A self‐tuned resonance?

Esler

Polvani

Scott

2006

Geophysical Research Letters

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The extraordinary Antarctic stratospheric warming event of 2002 was characterized by a remarkable vertical structure, with the vortex observed to divide at upper levels in the stratosphere but not at lower levels: such ‘partially’ split vortex events are relatively rare. A simple, yet fully three‐dimensional, model is constructed to investigate the dynamics of this unique event. Planetary waves are excited on the model vortex edge by a lower boundary forcing characterized by two parameters: an amplitude hF and a frequency ωF, measured relative to a stationary frame. For realistic forcing amplitudes, a partial vortex split resembling that observed during the 2002 event is found only within a specific, narrow band of forcing frequencies. Exploiting the relative simplicity of our model, these frequencies are shown to be those causing a ‘self‐tuning’ resonant excitation of the gravest linear mode, during which nonlinear feedback causes an initially off‐resonant forcing to approach resonance.

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Simulations of the February 1979 Stratospheric Sudden Warming: Model Comparisons and Three-Dimensional Evolution

Cited by 36 publications

References 0 publications

Observations of wintertime arctic mesosphere cooling associated with stratosphere baroclinic zones

Observations of wintertime arctic mesosphere cooling associated with stratosphere baroclinic zones

Stratospheric Sudden Warmings as Self-Tuning Resonances. Part I: Vortex Splitting Events

The Antarctic stratospheric sudden warming of 2002: A self‐tuned resonance?

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