Latitudinal Extension of Cooling and Upwelling Signals Associated with Stratospheric Sudden Warmings

Taguchi, Masakazu

doi:10.2151/jmsj.2011-511

Cited by 16 publications

(15 citation statements)

References 21 publications

(35 reference statements)

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“…According to commonly used criteria (Christiansen, 2001;Charlton and Polvani, 2007), we identify the warming event on 24 January by the reversal of 60 • N westerly zonal-mean wind at 10 hPa. As has been pointed out (Taguchi, 2011;Gómez-Escolar et al, 2014), use of the highest polar cap temperature instead of the zonal wind reversal at 60 • N and 10 hPa, characterizes the response of the BDC to SSWs better. Thus, we identify the central SSW day as the date when 5-day smoothed polar cap temperature at 10 hPa reach its peak within ±5 days of the wind reversal date.…”

Section: Dynamical Backgroundmentioning

confidence: 97%

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Tao¹,

Konopka²,

Ploeger³

et al. 2015

Atmos. Chem. Phys.

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Abstract. In a case study of a remarkable major sudden stratospheric warming (SSW) during the boreal winter 2008/09, we investigate how transport and mixing triggered by this event affected the composition of the entire stratosphere in the Northern Hemisphere. We simulate this event with the Chemical Lagrangian Model of the Stratosphere (CLaMS), both with optimized mixing parameters and with no mixing, i.e. with transport occurring only along the Lagrangian trajectories. The results are investigated by using tracer-tracer correlations and by applying the transformed Eulerian-mean formalism. The CLaMS simulation of N 2 O and O 3 , and in particular of the O 3 -N 2 O tracer correlations with optimized mixing parameters, shows good agreement with the Aura Microwave Limb Sounder (MLS) data. The spatial distribution of mixing intensity in CLaMS correlates fairly well with the Eliassen-Palm flux convergence. This correlation illustrates how planetary waves drive mixing. By comparing simulations with and without mixing, we find that after the SSW, poleward transport of air increases, not only across the vortex edge but also across the subtropical transport barrier. Moreover, the SSW event, at the same time, accelerates polar descent and tropical ascent of the BrewerDobson circulation. The accelerated ascent in the tropics and descent at high latitudes first occurs in the upper stratosphere and then propagates downward to the lower stratosphere. This downward propagation takes over 1 month from the potential temperature level of 1000 to 400 K.

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Section: Dynamical Backgroundmentioning

confidence: 97%

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Tao¹,

Konopka²,

Ploeger³

et al. 2015

Atmos. Chem. Phys.

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show abstract

“…The corresponding central dates, the first day when zonal wind reversed at 60°N and 10 hPa, are listed in Table (second column). As has been pointed out [ Taguchi , ; Gómez‐Escolar et al , ], use of the highest polar cap temperature instead of the zonal wind reversal at 60°N and 10 hPa, characterizes the response of the BDC to MWs better. Thus, in our study the MW central dates (Table , third column) are defined as the dates with highest mean polar cap temperature (60–90°N) within a ±30 day window around each MW central date derived from the wind criterion (CP07).…”

Section: Major Stratospheric Sudden Warmings and The Qbomentioning

confidence: 99%

“…The second column shows the central dates according to the wind reversal criterion of Charlton and Polvani []. The third column shows the central dates according to the maximum polar cap temperature [ Taguchi , ]. The QBO phase is defined by 30 day smoothed equatorial mean wind at θ = 500 K (∼50 hPa).…”

Section: Major Stratospheric Sudden Warmings and The Qbomentioning

confidence: 99%

Impact of stratospheric major warmings and the quasi‐biennial oscillation on the variability of stratospheric water vapor

Tao

Konopka

Ploeger

et al. 2015

Geophysical Research Letters

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Based on simulations with the Chemical Lagrangian Model of the Stratosphere for the 1979–2013 period, driven by the European Centre for Medium‐Range Weather Forecasts ERA‐Interim reanalysis, we analyze the impact of the quasi‐biennial oscillation (QBO) and of Major Stratospheric Warmings (MWs) on the amount of water vapor entering the stratosphere during boreal winter. The amplitude of H2O variation related to the QBO amounts to 0.5 ppmv. The additional effect of MWs reaches its maximum about 2–4 weeks after the central date of the MW and strongly depends on the QBO phase. Whereas during the easterly QBO phase there is a pronounced drying of about 0.3 ppmv about 3 weeks after the MW, the impact of the MW during the westerly QBO phase is smaller (about 0.2 ppmv) and more diffusely spread over time. We suggest that the MW‐associated enhanced dehydration combined with a higher frequency of MWs after the year 2000 may have contributed to the lower stratospheric water vapor after 2000.

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“…Large and simple structure of the temporal variation of the forcing (eddy heat flux) and the response (stratospheric zonal wind) of 2009 and 2010 SSWs permit us to investigate a detailed feature of the circulation change. It should also be noted that not all major SSW events necessarily have such large tropical impacts, as this depends on the latitude of the associated planetary wave breaking (Taguchi, 2011).…”

Section: Introductionmentioning

confidence: 99%

The role of convective overshooting clouds in tropical stratosphere–troposphere dynamical coupling

et al. 2015

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Abstract. This paper investigates the role of deep convection and overshooting convective clouds in stratospheretroposphere dynamical coupling in the tropics during two large major stratospheric sudden warming events in January 2009 and January 2010. During both events, convective activity and precipitation increased in the equatorial Southern Hemisphere as a result of a strengthening of the BrewerDobson circulation induced by enhanced stratospheric planetary wave activity. Correlation coefficients between variables related to the convective activity and the vertical velocity were calculated to identify the processes connecting stratospheric variability to the troposphere. Convective overshooting clouds showed a direct relationship to lower stratospheric upwelling at around 70-50 hPa. As the tropospheric circulation change lags behind that of the stratosphere, outgoing longwave radiation shows almost no simultaneous correlation with the stratospheric upwelling. This result suggests that the stratospheric circulation change first penetrates into the troposphere through the modulation of deep convective activity.

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Latitudinal Extension of Cooling and Upwelling Signals Associated with Stratospheric Sudden Warmings

Cited by 16 publications

References 21 publications

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Impact of the 2009 major sudden stratospheric warming on the composition of the stratosphere

Impact of stratospheric major warmings and the quasi‐biennial oscillation on the variability of stratospheric water vapor

The role of convective overshooting clouds in tropical stratosphere–troposphere dynamical coupling

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