scholarly journals A simple kinematic model for the Lagrangian description of relevant nonlinear processes in the stratospheric polar vortex

2017 ◽  
Vol 24 (2) ◽  
pp. 265-278 ◽  
Author(s):  
Víctor José García-Garrido ◽  
Jezabel Curbelo ◽  
Carlos Roberto Mechoso ◽  
Ana María Mancho ◽  
Stephen Wiggins
Keyword(s):  
Vortex Breakdown ◽  
Kinematic Model ◽  
Axisymmetric Flow ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Lagrangian Description ◽  
Stratospheric Polar Vortex ◽  
Fourier Decomposition ◽  
Complex Fluid ◽  
Hyperbolic Trajectories

Abstract. In this work, we study the Lagrangian footprint of the planetary waves present in the Southern Hemisphere stratosphere during the exceptional sudden Stratospheric warming event that took place during September 2002. Our focus is on constructing a simple kinematic model that retains the fundamental mechanisms responsible for complex fluid parcel evolution, during the polar vortex breakdown and its previous stages. The construction of the kinematic model is guided by the Fourier decomposition of the geopotential field. The study of Lagrangian transport phenomena in the ERA-Interim reanalysis data highlights hyperbolic trajectories, and these trajectories are Lagrangian objects that are the kinematic mechanism for the observed filamentation phenomena. Our analysis shows that the breaking and splitting of the polar vortex is justified in our model by the sudden growth of a planetary wave and the decay of the axisymmetric flow.

scholarly journals A Simple Kinematic Model for the Lagrangian Description of Relevant Nonlinear Processes in the Stratospheric Polar Vortex

2016 ◽  
Author(s):  
Victor José García-Garrido ◽  
Jezabel Curbelo ◽  
Carlos Roberto Mechoso ◽  
Ana María Mancho ◽  
Stephen Wiggins
Keyword(s):  
Kinematic Model ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Planetary Waves ◽  
Lagrangian Description ◽  
Lagrangian Analysis ◽  
Mixing Processes ◽  
Geometrical Structures ◽  
Stratospheric Polar Vortex ◽  
Fourier Decomposition

Abstract. In this work we study the Lagrangian footprint of the planetary waves present in the Southern Hemisphere stratosphere during the Sudden Stratospheric Warming event that took place during September 2002. The Lagrangian analysis of the transport and mixing processes is carried out in the framework of dynamical systems theory, by means of a Lagrangian descriptor. We seek to describe the Lagrangian skeleton of geometrical structures that lead to filamentation phenomena and the breakdown of the polar vortex, and establish its relation with how planetary waves interact. Our approach is based on the construction of a simple kinematic model, inspired by the Fourier decomposition of the geopotential field. We show that this model is capable of reproducing the key Lagrangian features present on the reanalysis data such as the formation of filaments eroding the stratospheric polar vortex and the breakdown of the vortex.

scholarly journals Nonstationarity in Southern Hemisphere Climate Variability Associated with the Seasonal Breakdown of the Stratospheric Polar Vortex

2017 ◽  
Vol 30 (18) ◽  
pp. 7125-7139 ◽  
Author(s):  
Nicholas J. Byrne ◽  
Theodore G. Shepherd ◽  
Tim Woollings ◽  
R. Alan Plumb
Keyword(s):  
Climate Variability ◽  
Southern Hemisphere ◽  
Seasonal Cycle ◽  
Vortex Breakdown ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Early Summer ◽  
Stratospheric Polar Vortex ◽  
Time Symmetry

Abstract Statistical models of climate generally regard climate variability as anomalies about a climatological seasonal cycle, which are treated as a stationary stochastic process plus a long-term seasonally dependent trend. However, the climate system has deterministic aspects apart from the climatological seasonal cycle and long-term trends, and the assumption of stationary statistics is only an approximation. The variability of the Southern Hemisphere zonal-mean circulation in the period encompassing late spring and summer is an important climate phenomenon and has been the subject of numerous studies. It is shown here, using reanalysis data, that this variability is rendered highly nonstationary by the organizing influence of the seasonal breakdown of the stratospheric polar vortex, which breaks time symmetry. It is argued that the zonal-mean tropospheric circulation variability during this period is best viewed as interannual variability in the transition between the springtime and summertime regimes induced by variability in the vortex breakdown. In particular, the apparent long-term poleward jet shift during the early-summer season can be more simply understood as a delay in the equatorward shift associated with this regime transition. The implications of such a perspective for various open questions are discussed.

scholarly journals Influence of the Quasi-Biennial Oscillation on the Extratropical Winter Stratosphere in an Atmospheric General Circulation Model and in Reanalysis Data

2010 ◽  
Vol 67 (5) ◽  
pp. 1402-1419 ◽  
Author(s):  
James A. Anstey ◽  
Theodore G. Shepherd ◽  
John F. Scinocca
Keyword(s):  
Zonal Wind ◽  
General Circulation ◽  
Polar Vortex ◽  
Reanalysis Data ◽  
Empirical Orthogonal Functions ◽  
Vertical Profiles ◽  
Quasi Biennial Oscillation ◽  
Stratospheric Polar Vortex ◽  
Atmospheric General Circulation ◽  
Biennial Oscillation

Abstract The interannual variability of the stratospheric polar vortex during winter in both hemispheres is observed to correlate strongly with the phase of the quasi-biennial oscillation (QBO) in tropical stratospheric winds. It follows that the lack of a spontaneously generated QBO in most atmospheric general circulation models (AGCMs) adversely affects the nature of polar variability in such models. This study examines QBO–vortex coupling in an AGCM in which a QBO is spontaneously induced by resolved and parameterized waves. The QBO–vortex coupling in the AGCM compares favorably to that seen in reanalysis data [from the 40-yr ECMWF Re-Analysis (ERA-40)], provided that careful attention is given to the definition of QBO phase. A phase angle representation of the QBO is employed that is based on the two leading empirical orthogonal functions of equatorial zonal wind vertical profiles. This yields a QBO phase that serves as a proxy for the vertical structure of equatorial winds over the whole depth of the stratosphere and thus provides a means of subsampling the data to select QBO phases with similar vertical profiles of equatorial zonal wind. Using this subsampling, it is found that the QBO phase that induces the strongest polar vortex response in early winter differs from that which induces the strongest late-winter vortex response. This is true in both hemispheres and for both the AGCM and ERA-40. It follows that the strength and timing of QBO influence on the vortex may be affected by the partial seasonal synchronization of QBO phase transitions that occurs both in observations and in the model. This provides a mechanism by which changes in the strength of QBO–vortex correlations may exhibit variability on decadal time scales. In the model, such behavior occurs in the absence of external forcings or interannual variations in sea surface temperatures.

scholarly journals Predictability of the stratospheric polar vortex breakdown: An ensemble reforecast experiment for the splitting event in January 2009

2016 ◽  
Vol 121 (7) ◽  
pp. 3388-3404 ◽  
Author(s):  
Shunsuke Noguchi ◽  
Hitoshi Mukougawa ◽  
Yuhji Kuroda ◽  
Ryo Mizuta ◽  
Shoukichi Yabu ◽  
...  
Keyword(s):  
Vortex Breakdown ◽  
Polar Vortex ◽  
Stratospheric Polar Vortex

scholarly journals Dynamical and chemical processes contributing to ozone loss in exceptional Arctic stratosphere winter-spring of 2020

2021 ◽  
Author(s):  
Sergei P. Smyshlyaev ◽  
Pavel N. Vargin ◽  
Alexander N. Lukyanov ◽  
Natalia D. Tsvetkova ◽  
Maxim A. Motsakov
Keyword(s):  
Polar Vortex ◽  
Reanalysis Data ◽  
Chemical Processes ◽  
Western Hemisphere ◽  
The Arctic ◽  
Spring Season ◽  
Dynamical Processes ◽  
Stratospheric Polar Vortex ◽  
Ozone Loss ◽  
Eastern Hemisphere

Abstract. The features of dynamical processes and changes in the ozone layer in the Arctic stratosphere during the winter-spring season 2019–2020 are analyzed using ozonesondes, reanalysis data and numerical experiments with a chemistry-transport model (CTM). Using the trajectory model of the Central Aerological Observatory (TRACAO) and the ERA5 reanalysis ozone mixing ratio data, a comparative analysis of the evolution of stratospheric ozone averaged along the trajectories in the winter-spring seasons of 2010–2011, 2015–2016, and 2019–2020 was carried out, which demonstrated that the largest ozone loss at altitudes of 18–20 km within stratospheric polar vortex in the Arctic in winter-spring 2019–2020 exceeded the corresponding values of the other two winter-spring seasons 2010–2011 and 2015–2016 with the largest decrease in ozone content in recent year. The total decrease in the column ozone inside the stratospheric polar vortex, calculated using the vertical ozone profiles obtained based on the ozonesondes data, in the 2019–2020 winter-spring season was more than 150 Dobson Units, which repeated the record depletion for the 2010–2011 winter-spring season. At the same time, the maximum ozone loss in winter 2019–2020 was observed at lower levels than in 2010–2011, which is consistent with the results of trajectory analysis and the results of other authors. The results of numerical calculations with the CTM with dynamical parameters specified from the MERRA-2 reanalysis data, carried out according to several scenarios of accounting for the chemical destruction of ozone, indicated that both dynamical and chemical processes make contributions to ozone loss inside the polar vortex. In this case, dynamical processes predominate in the western hemisphere, while in the eastern hemisphere chemical processes make an almost equal contribution with dynamical factors, and the chemical depletion of ozone is determined not only by heterogeneous processes on the surface of the polar stratospheric clouds, but by the gas-phase destruction in nitrogen catalytic cycles as well.

Understanding the role of the troposphere in the surface impact of the 2018 sudden stratospheric warming event

2021 ◽  
Author(s):  
Juan J. González-Alemán ◽  
Christian M. Grams ◽  
Blanca Ayarzagüena ◽  
Pablo Zurita-Gotor ◽  
Daniela I. V. Domeisen Domeisen ◽  
...  
Keyword(s):  
North Atlantic ◽  
Vortex Breakdown ◽  
Rapid Change ◽  
Polar Vortex ◽  
The Arctic ◽  
Lead Times ◽  
Strong Impact ◽  
Ensemble Forecasts ◽  
Stratospheric Polar Vortex ◽  
The North

<p>Sudden stratospheric warmings (SSWs) are impressive phenomena that consist of a rapid stratospheric polar vortex breakdown. SSWs can have a strong impact on the tropospheric weather and are mainly associated with the negative phases of the Arctic and North Atlantic Oscillations (AO, NAO), and with northern European cold outbreaks, thus causing high societal impact. However, the mechanisms behind the downward impact from the stratosphere are insufficiently understood, especially the role played by the troposphere. In this work, we investigate this coupling and its associated predictability limits by studying the 2018 SSW event.</p><p>By analyzing ECMWF 15-day ensemble forecasts and partitioning them into different weather regimes, we search for possible dynamical tropospheric events that may have favored the downward stratosphere-troposphere coupling during and after the SSW. It is found that two cyclogenesis events were the main drivers of the negative NAO pattern associated with a Greenland Blocking, causing a rapid change from prevailing westerlies into a blocked state in the North Atlantic region. Unless these cyclogenesis events are simulated in the forecasts, the prediction of a Greenland Blocking does not become highly prevalent. No important stratospheric differences between WRs were found. A possible oceanic contribution to this blocked state is also found. This work corroborates that individual synoptic events might constitute a “predictability barrier" for subsequent forecast lead times. It also sheds light, on the specific topic of troposphere-stratosphere coupling.</p>

scholarly journals Stratéole/Vorcore—Long-duration, Superpressure Balloons to Study the Antarctic Lower Stratosphere during the 2005 Winter

2007 ◽  
Vol 24 (12) ◽  
pp. 2048-2061 ◽  
Author(s):  
Albert Hertzog ◽  
Philippe Cocquerez ◽  
René Guilbon ◽  
Jean-Noël Valdivia ◽  
Stéphanie Venel ◽  
...  
Keyword(s):  
Lower Stratosphere ◽  
Vortex Breakdown ◽  
Polar Vortex ◽  
Summer Circulation ◽  
Stratospheric Polar Vortex ◽  
Long Duration ◽  
Independent Observations ◽  
Lagrangian Tracers ◽  
The Antarctic ◽  
Gps Observations

Abstract In September and October 2005, the Stratéole/Vorcore campaign flew 27 superpressure balloons from McMurdo, Antarctica, into the stratospheric polar vortex. Long-duration flights were successfully achieved, 16 of those flights lasting for more than 2 months. Most flights were terminated because they flew out of the authorized flight domain or because of energy shortage in the gondola. The atmospheric pressure (1-Pa precision) was measured every minute during the flights, whereas air temperature observations (0.25-K accuracy) and balloon positions (absolute GPS observations, 10-m accuracy) were obtained every 15 min. Fifteen-minute-averaged horizontal velocities of the wind were deduced from the successive balloon positions with a corresponding accuracy ≲0.1 m s−1. The collected dataset (more than 150 000 independent observations) provides a thorough high-resolution sampling of the polar lower stratosphere in the Southern Hemisphere from its wintertime state up to the establishment of the summer circulation in December–January. Most of the balloons stayed inside the vortex until its final breakdown, although a few were ejected toward the midlatitudes in November during filamention events associated with an increase in planetary wave activity. The balloons behaved as quasi-Lagrangian tracers during the first part of the campaign (quiescent vortex) and after the vortex breakdown in early December. Large-amplitude mountain gravity waves were detected over the Antarctic Peninsula and caused one flight termination associated with the sudden burst in the balloon superpressure.

Sign in / Sign up

Export Citation Format

Share Document