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1. Introduction The Brewer–Dobson circulation (BDC) is the slow meridional overturning circulation of the stratosphere, consisting of upwelling through the tropical tropopause, then poleward motion and downwelling through the midlatitudes and at the poles. This circulation is critical for the vertical transport of tracers such as ozone, volcanic aerosols, and chlorofluorocarbons (CFCs); for the temperature of the tropical tropopause and consequently the amount of water vapor in the stratosphere
1. Introduction The Brewer–Dobson circulation (BDC) is the slow meridional overturning circulation of the stratosphere, consisting of upwelling through the tropical tropopause, then poleward motion and downwelling through the midlatitudes and at the poles. This circulation is critical for the vertical transport of tracers such as ozone, volcanic aerosols, and chlorofluorocarbons (CFCs); for the temperature of the tropical tropopause and consequently the amount of water vapor in the stratosphere
1. Introduction During Northern Hemisphere (NH) winter, the stratosphere deviates significantly from radiative equilibrium because of the interaction of the stratospheric zonal-mean flow and planetary-scale waves, which propagate upward from the troposphere. The convergence of Eliassen–Palm (EP) flux by planetary-scale waves drives the equator-to-pole residual circulation that produces upwelling in the tropics and downwelling in high latitudes ( Dunkerton et al. 1981 ; McIntyre and Palmer 1983
1. Introduction During Northern Hemisphere (NH) winter, the stratosphere deviates significantly from radiative equilibrium because of the interaction of the stratospheric zonal-mean flow and planetary-scale waves, which propagate upward from the troposphere. The convergence of Eliassen–Palm (EP) flux by planetary-scale waves drives the equator-to-pole residual circulation that produces upwelling in the tropics and downwelling in high latitudes ( Dunkerton et al. 1981 ; McIntyre and Palmer 1983
weather ( Thompson and Wallace 2001 ; Baldwin et al. 2003 ). These annular modes occur in both the Northern and Southern Hemispheres [i.e., the Northern Annular Mode (NAM) and the Southern Annular Mode (SAM)] and over a wide range of time scales (weeks to decades). Most recent research examining connections between the stratospheric polar vortex and tropospheric circulation patterns has focused on either subseasonal variability (e.g., Limpasuvan et al. 2004 ; McDaniel and Black 2005 ) or long
weather ( Thompson and Wallace 2001 ; Baldwin et al. 2003 ). These annular modes occur in both the Northern and Southern Hemispheres [i.e., the Northern Annular Mode (NAM) and the Southern Annular Mode (SAM)] and over a wide range of time scales (weeks to decades). Most recent research examining connections between the stratospheric polar vortex and tropospheric circulation patterns has focused on either subseasonal variability (e.g., Limpasuvan et al. 2004 ; McDaniel and Black 2005 ) or long
switches sign. In the stratosphere, during NH winter, the polar vortex is warmer and more disturbed during warm ENSO events (e.g., Sassi et al. 2004 ; Manzini et al. 2006 ; Garcia-Herrera et al. 2006 ; Taguchi and Hartmann 2006 ). As well as this high-latitude response there is also an altered circulation in the low-latitude lower stratosphere. During warm ENSO conditions there is enhanced upwelling in the tropical lower stratosphere, which is accompanied by cooler temperatures ( Reid et al. 1989
switches sign. In the stratosphere, during NH winter, the polar vortex is warmer and more disturbed during warm ENSO events (e.g., Sassi et al. 2004 ; Manzini et al. 2006 ; Garcia-Herrera et al. 2006 ; Taguchi and Hartmann 2006 ). As well as this high-latitude response there is also an altered circulation in the low-latitude lower stratosphere. During warm ENSO conditions there is enhanced upwelling in the tropical lower stratosphere, which is accompanied by cooler temperatures ( Reid et al. 1989
1. Introduction The Brewer–Dobson circulation (BDC; Dobson et al. 1929 ; Brewer 1949 ; Dobson 1956 ) is a slow, hemispheric-scale, meridional overturning circulation in the stratosphere, with air moving upward in the tropics and poleward and downward at higher latitudes. The BDC consists of a “shallow” branch, a strong circulation driven by wave breaking in the lower stratosphere, juxtaposed on a “deep” branch, a weaker circulation driven by planetary waves breaking in the middle and upper
1. Introduction The Brewer–Dobson circulation (BDC; Dobson et al. 1929 ; Brewer 1949 ; Dobson 1956 ) is a slow, hemispheric-scale, meridional overturning circulation in the stratosphere, with air moving upward in the tropics and poleward and downward at higher latitudes. The BDC consists of a “shallow” branch, a strong circulation driven by wave breaking in the lower stratosphere, juxtaposed on a “deep” branch, a weaker circulation driven by planetary waves breaking in the middle and upper
intertropical convergence zone (ITCZ) ( Lau and Kim 2015 ; Byrne et al. 2018 ). Likewise, models show that the lower stratospheric circulation also responds to increased CO 2 with a narrowing and acceleration of the Brewer–Dobson circulation (BDC) ( Lin and Fu 2013 ; Butchart et al. 2006 ; Eichelberger and Hartmann 2005 ). However, there remains uncertainty in the mechanisms of these changes, and it is not well known how tightly coupled features are to one another. For example, there has been interest
intertropical convergence zone (ITCZ) ( Lau and Kim 2015 ; Byrne et al. 2018 ). Likewise, models show that the lower stratospheric circulation also responds to increased CO 2 with a narrowing and acceleration of the Brewer–Dobson circulation (BDC) ( Lin and Fu 2013 ; Butchart et al. 2006 ; Eichelberger and Hartmann 2005 ). However, there remains uncertainty in the mechanisms of these changes, and it is not well known how tightly coupled features are to one another. For example, there has been interest
1. Introduction The Brewer–Dobson circulation (BDC) characterizes the transport of mass through the stratosphere, a slow upwelling in the tropics, poleward drift through the midlatitudes, and descent in the middle and high latitudes. Dobson et al. (1929) first speculated on the existence of this transport based on the positive equator-to-pole gradient in stratospheric ozone in the boreal spring, a gradient seemingly at odds with the (then) hypothesis that ozone is produced by solar radiation
1. Introduction The Brewer–Dobson circulation (BDC) characterizes the transport of mass through the stratosphere, a slow upwelling in the tropics, poleward drift through the midlatitudes, and descent in the middle and high latitudes. Dobson et al. (1929) first speculated on the existence of this transport based on the positive equator-to-pole gradient in stratospheric ozone in the boreal spring, a gradient seemingly at odds with the (then) hypothesis that ozone is produced by solar radiation
levels in the troposphere. In this contribution, we highlight the influence of ACRE on the stratospheric circulation, which to our knowledge has not been emphasized in previous work. The current study may be viewed as a companion study to Li et al. (2015) . In that study, we demonstrated that ACRE have a robust influence on the simulated global tropospheric circulation. Here we demonstrate that ACRE also have a robust influence on the global stratospheric circulation. 2. Numerical experiments There
levels in the troposphere. In this contribution, we highlight the influence of ACRE on the stratospheric circulation, which to our knowledge has not been emphasized in previous work. The current study may be viewed as a companion study to Li et al. (2015) . In that study, we demonstrated that ACRE have a robust influence on the simulated global tropospheric circulation. Here we demonstrate that ACRE also have a robust influence on the global stratospheric circulation. 2. Numerical experiments There
1. Introduction Climate models predict that there will be a substantial warming of the earth’s atmosphere by the end of the twenty-first century, accompanied by significant changes in the general circulation of the troposphere and stratosphere, if anthropogenic greenhouse gas (GHG) emissions are not abated. Coupled atmosphere–ocean climate models project that the tropospheric extratropical jets will shift poleward (e.g., Yin 2005 ; Miller et al. 2006 ), accompanied by an expansion of the
1. Introduction Climate models predict that there will be a substantial warming of the earth’s atmosphere by the end of the twenty-first century, accompanied by significant changes in the general circulation of the troposphere and stratosphere, if anthropogenic greenhouse gas (GHG) emissions are not abated. Coupled atmosphere–ocean climate models project that the tropospheric extratropical jets will shift poleward (e.g., Yin 2005 ; Miller et al. 2006 ), accompanied by an expansion of the
; Smith et al. 2001 ; Solomon et al. 2010 ). However, there is now compelling evidence that the stratosphere and troposphere act as a two-way dynamically coupled system, such that changes in stratospheric wind and temperature have an impact on the extratropical tropospheric circulation [for an overview, see, e.g., Gerber et al. (2012) ]. This study therefore considers an additional mechanism—specifically, that trends in SWV will cause changes in stratospheric temperature and wind, which may impact
; Smith et al. 2001 ; Solomon et al. 2010 ). However, there is now compelling evidence that the stratosphere and troposphere act as a two-way dynamically coupled system, such that changes in stratospheric wind and temperature have an impact on the extratropical tropospheric circulation [for an overview, see, e.g., Gerber et al. (2012) ]. This study therefore considers an additional mechanism—specifically, that trends in SWV will cause changes in stratospheric temperature and wind, which may impact
