scholarly journals Climatic variability of the stratosphere-troposphere coupling during the last decades

К.А. Диденко ◽  
Т.С. Ермакова ◽  
А.И. Погорельцев ◽  
Е.В. Ракушина

В данной работе показано, как изменялось взаимодействие между тропосферой и стратосферой в последние десятилетия. Также оценено влияние таких явлений, как квазидвухлетнее колебание (КДК) на данное взаимодействие. Для этого было проанализировано распространение планетарных волн в атмосфере с использованием трехмерных потоков волновой активности, показана временная изменчивость потоков и линейный тренд. Кроме того, была оценена реакция тропосферы над Сибирью и Восточной Азией на КДК. The study of the variability of stratosphere-troposphere coupling during the last decades is considered. The influence of such phenomena as quasi-biennial oscillation (QBO) on this interaction was also estimated. For this, the propagation of planetary waves in the atmosphere was analyzed using three-dimensional wave activity fluxes. The temporal variability of fluxes and a linear trend was shown. In addition, the response of the troposphere over Siberia and East Asia to the QBO was assessed.

2018 ◽  
Vol 75 (1) ◽  
pp. 21-40 ◽  
Peter Hitchcock ◽  
Peter H. Haynes ◽  
William J. Randel ◽  
Thomas Birner

A configuration of an idealized general circulation model has been obtained in which a deep, stratospheric, equatorial, westerly jet is established that is spontaneously and quasi-periodically disrupted by shallow easterly jets. Similar to the disruption of the quasi-biennial oscillation (QBO) observed in early 2016, meridional fluxes of wave activity are found to play a central role. The possible relevance of two feedback mechanisms to these disruptions is considered. The first involves the secondary circulation produced in the shear zones on the upper and lower flanks of the easterly jet. This is found to play a role in maintaining the aspect ratio of the emerging easterly jet. The second involves the organization of the eddy fluxes by the mean flow: the presence of a weak easterly anomaly within a tall, tropical, westerly jet is demonstrated to produce enhanced and highly focused wave activity fluxes that reinforce and strengthen the easterly anomalies. The eddies appear to be organized by the formation of strong potential vorticity gradients on the subtropical flanks of the easterly anomaly. Similar wave activity and potential vorticity structures are found in the ERA-Interim for the observed QBO disruption, indicating this second feedback was active then.

2013 ◽  
Vol 70 (6) ◽  
pp. 1603-1615 ◽  
Takenari Kinoshita ◽  
Kaoru Sato

Abstract A companion paper formulates the three-dimensional wave activity flux (3D-flux-M) whose divergence corresponds to the wave forcing on the primitive equations. However, unlike the two-dimensional wave activity flux, 3D-flux-M does not accurately describe the magnitude and direction of wave propagation. In this study, the authors formulate a modification of 3D-flux-M (3D-flux-W) to describe this propagation using small-amplitude theory for a slowly varying time-mean flow. A unified dispersion relation for inertia–gravity waves and Rossby waves is also derived and used to relate 3D-flux-W to the group velocity. It is shown that 3D-flux-W and the modified wave activity density agree with those for inertia–gravity waves under the constant Coriolis parameter assumption and those for Rossby waves under the small Rossby number assumption. To compare 3D-flux-M with 3D-flux-W, an analysis of the European Centre for Medium-Range Weather Forecasts (ECMWF) Interim Re-Analysis (ERA-Interim) data is performed focusing on wave disturbances in the storm tracks during April. While the divergence of 3D-flux-M is in good agreement with the meridional component of the 3D residual mean flow associated with disturbances, the 3D-flux-W divergence shows slight differences in the upstream and downstream regions of the storm tracks. Further, the 3D-flux-W magnitude and direction are in good agreement with those derived by R. A. Plumb, who describes Rossby wave propagation. However, 3D-flux-M is different from Plumb’s flux in the vicinity of the storm tracks. These results suggest that different fluxes (both 3D-flux-W and 3D-flux-M) are needed to describe wave propagation and wave–mean flow interaction in the 3D formulation.

2008 ◽  
Vol 21 (18) ◽  
pp. 4664-4679 ◽  
Manuel Pulido ◽  
John Thuburn

Abstract Using a variational technique, middle atmosphere gravity wave drag (GWD) is estimated from Met Office middle atmosphere analyses for the year 2002. The technique employs an adjoint model of a middle atmosphere dynamical model to minimize a cost function that measures the differences between the model state and observations. The control variables are solely the horizontal components of GWD; therefore, the minimization determines the optimal estimate of the drag. For each month, Met Office analyses are taken as the initial condition for the first day of the month, and also as observations for each successive day. In this way a three-dimensional GWD field is obtained for the entire year with a temporal resolution of 1 day. GWD shows a pronounced seasonal cycle. During solstices, there are deceleration regions of the polar jet centered at about 63° latitude in the winter hemisphere, with a peak of 49 m s−1 day−1 at 0.24 hPa in the Southern Hemisphere; the summer hemisphere also shows a deceleration region but much weaker, with a peak of 24 m s−1 day−1 centered at 45° latitude and 0.6 hPa. During equinoxes GWD is weak and exhibits a smooth transition between the winter and summer situation. The height and latitude of the deceleration center in both winter and summer hemispheres appear to be constant. Important longitudinal dependencies in GWD are found that are related to planetary wave activity; GWD intensifies in the exit region of jet streaks. In the lower tropical stratosphere, the estimated GWD shows a westward GWD descending together with the westward phase of the quasi-biennial oscillation. Above, GWD exhibits a semiannual pattern that is approximately out of phase with the semiannual oscillation in the zonal wind. Furthermore, a descending GWD pattern is found at those heights, similar in magnitude and sign to that in the lower stratosphere.

2005 ◽  
Vol 62 (12) ◽  
pp. 4178-4195 ◽  
Lucy J. Campbell ◽  
Theodore G. Shepherd

Abstract Parameterization schemes for the drag due to atmospheric gravity waves are discussed and compared in the context of a simple one-dimensional model of the quasi-biennial oscillation (QBO). A number of fundamental issues are examined in detail, with the goal of providing a better understanding of the mechanism by which gravity wave drag can produce an equatorial zonal wind oscillation. The gravity wave–driven QBOs are compared with those obtained from a parameterization of equatorial planetary waves. In all gravity wave cases, it is seen that the inclusion of vertical diffusion is crucial for the descent of the shear zones and the development of the QBO. An important difference between the schemes for the two types of waves is that in the case of equatorial planetary waves, vertical diffusion is needed only at the lowest levels, while for the gravity wave drag schemes it must be included at all levels. The question of whether there is downward propagation of influence in the simulated QBOs is addressed. In the gravity wave drag schemes, the evolution of the wind at a given level depends on the wind above, as well as on the wind below. This is in contrast to the parameterization for the equatorial planetary waves in which there is downward propagation of phase only. The stability of a zero-wind initial state is examined, and it is determined that a small perturbation to such a state will amplify with time to the extent that a zonal wind oscillation is permitted.

2020 ◽  
Yuanyuan Han ◽  
Wenshou Tian ◽  
Fei Xie

<p>Stratospheric hydrogen chloride (HCl) is the main stratospheric reservoir of chlorine, deriving from the decomposition of chlorine-containing source gases. Its trend has been used as a metrics of ozone depletion or recovery. Using the latest satellite observations, the authors find that a significant increase of Northern Hemisphere stratospheric HCl during 2010–2011 can mislead trends of HCl in recent decades. Agree with previous studies, HCl increased from 2005 to 2011; while when removing the large increase of stratospheric HCl during 2010–2011, the increasing linear trend from 2005 to 2011 becomes weak and insignificant, in addition, the linear trend of Northern Hemisphere stratospheric HCl from 2005 to 2016 also shows weak and insignificant. The significant increase of HCl during 2010–2011 is attributed to a super strong north polar vortex and a reduced residual circulation during 2010–2011, which slowed down the transport of HCl from the low–mid latitudes to the high latitudes, leading to accumulation of HCl in the middle latitudes of the stratosphere during 2010–2011. Further analysis suggests that the strong polar vortex and the reduced residual circulation were caused by the joint effect of a La Niña event and the west phase of the quasi-biennial oscillation.</p>

1976 ◽  
Vol 6 (4) ◽  
pp. 481-493 ◽  
J. Murray Mitchell

A variance spectrum of climatic variability is presented that spans all time scales of variability from about one hour (10−4 years) to the age of the Earth (4 × 109 years). An interpretive overview of the spectrum is offered in which a distinction is made between sources of variability that arise through stochastic mechanisms internal to the climatic system (atmosphere-ocean-cryosphere) and those that arise through forcing of the system from the outside. All identifiable mechanisms, both internal and external, are briefly defined and clarified as to their essential nature. It is concluded that most features of the spectrum of climatic variability can be given tentatively reasonable interpretations, whereas some features (in particular the quasi-biennial oscillation and the neoglacial cycle of the Holocene) remain fundamentally unexplained. The overall spectrum suggests the existence of a modest degree of deterministic forms of climatic change, but sufficient nonsystematic variability to place significant constraints both on the extent to which climate can be predicted, and on the extent to which significant events in the paleoclimatic record can ever manage to be assigned specific causes.

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