The Influence of the Quasi-Biennial Oscillation on the Troposphere in Winter in a Hierarchy of Models. Part II: Perpetual Winter WACCM Runs

Garfinkel, Chaim I.; Hartmann, Dennis L.

doi:10.1175/2011jas3702.1

Cited by 70 publications

(72 citation statements)

References 41 publications

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“…A horseshoe‐like structure of anomalous easterly winds emerges with anomalies maximizing just above the tropopause in the subtropics, and reaching down into the troposphere. This pattern is similar to the zonal wind anomalies that accompany the easterly phase of the QBO shown by Garfinkel and Hartmann (), and it is likely that similar dynamics are at play here. In the feedback simulation, throughout the troposphere, the zonal mean westerlies are reduced at around 45° latitude in both hemispheres, with changes being statistically significant between 2020 and 2039 in the SH, and significant in both hemispheres later in the simulation.…”

Section: Resultssupporting

confidence: 88%

Stratospheric Response in the First Geoengineering Simulation Meeting Multiple Surface Climate Objectives

et al. 2018

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We describe here changes in stratospheric dynamics and chemistry in a first century‐long sulfate aerosol geoengineering simulation in which the mean surface temperature and the interhemispheric and equator‐to‐pole surface temperature gradients were kept near their 2020 levels despite the RCP8.5 emission scenario. Simulations were carried out with the Community Earth System Model, version 1 with the Whole Atmosphere Community Climate Model as its atmospheric component [CESM1(WACCM)] coupled to a feedback algorithm controlling the magnitude of sulfur dioxide (SO2) injections at four injection latitudes. We find that, throughout the entire geoengineering simulation, the lower stratospheric temperatures increase by ∼0.19 K per Tg SO2 injection per year or ∼10 K with ∼40 Tg SO2/year total SO2 injection. These temperature changes are associated with a strengthening of the polar jets in the stratosphere and weakening of the mean zonal wind in the lower stratosphere subtropics and throughout the troposphere, associated with weaker storm track activity. In the geoengineering simulation the quasi‐biennial oscillation of the tropical lower stratospheric winds remains close to the presently observed quasi‐biennial oscillation, even for large amounts of SO2 injection. Water vapor in the stratosphere increases substantially: by 25% with ∼20 Tg SO2/year annual injection and by up to 90% with a ∼40 Tg SO2/year injection. Stratospheric column ozone in the geoengineering simulation is predicted to recover to or supersede preozone hole conditions by the end of the century.

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Section: Resultssupporting

confidence: 88%

Stratospheric Response in the First Geoengineering Simulation Meeting Multiple Surface Climate Objectives

et al. 2018

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“…There has been long-standing observational study of the QBO influence on Atlantic hurricane activity (e.g., Gray et al 1993;Camargo and Sobel 2010). Some recent studies find that the QBO can influence tropical convection, especially in the tropical Pacific (Garfinkel and Hartmann 2011;Liess and Geller 2012). The present work suggests that an important research for future is the understanding and quantifying of the extent of the stratospheric influence on the underlying tropical troposphere.…”

Section: Summary and Discussionmentioning

confidence: 70%

The Influence of the QBO on the Propagation of Equatorial Waves into the Stratosphere

Yang

Hoskins

Gray

2012

Journal of the Atmospheric Sciences

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The variation of stratospheric equatorial wave characteristics with the phase of the quasi-biennial oscillation (QBO) is investigated using ECMWF Re-Analysis and NOAA outgoing longwave radiation (OLR) data. The impact of the QBO phases on the upward propagation of equatorial waves is found to be consistent and significant. In the easterly phase, there is larger Kelvin wave amplitude but smaller westward-moving mixed Rossby-gravity (WMRG) and n 5 1 Rossby (R1) wave amplitude due to reduced propagation from the upper troposphere into the lower stratosphere, compared with the westerly phase. Differences in the wave amplitude exist in a deeper layer in summer than in winter, consistent with the seasonality of ambient zonal winds. There is a strong evidence of Kelvin wave amplitude peaking just below the descending westerly phase, suggesting that Kelvin waves act to bring the westerly phase downward. However, the corresponding evidence for WMRG and R1 waves is less clear.In the lower stratosphere there is zonal variation in equatorial waves. This reflects the zonal asymmetry of wave amplitudes in the upper troposphere, the source for the lower-stratospheric waves. In easterly winters the upper-tropospheric WMRG and R1 waves over the eastern Pacific region appear to be somewhat stronger compared to climatology, perhaps because of the accumulation of waves that are unable to propagate upward into the lower stratosphere. Vertical propagation features of these waves are generally consistent with theory and suggest a mixture of Doppler shifting by ambient flows and filtering. Some lower-stratosphere equatorial waves have a connection with preceding tropical convection, especially for Kelvin and R1 waves in winter.

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“…Collimore et al, 2003;Huang et al, 2012;Liess and Geller, 2012) or models (e.g. Giorgetta et al, 1999;Garfinkel and Hartmann, 2011;Nie and Sobel, 2015). Several mechanisms have been suggested as to how a link might proceed.…”

Section: The Qbo Effect On Snow Covermentioning

confidence: 99%

“…However, the role of clouds and other feedbacks is not well understood (e.g. Garfinkel and Hartmann, 2011). According to the wind shear mechanism, lower shear would favour deeper convection.…”

Section: The Qbo Effect On Snow Covermentioning

confidence: 99%

Multidecadal variations of the effects of the Quasi-Biennial Oscillation on the climate system

et al. 2016

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Abstract. Effects of the Quasi-Biennial Oscillation (QBO) on tropospheric climate are not always strong or they appear only intermittently. Studying them requires long time series of both the QBO and climate variables, which has restricted previous studies to the past 30-50 years. Here we use the benefits of an existing QBO reconstruction back to 1908. We first investigate additional, newly digitized historical observations of stratospheric winds to test the reconstruction. Then we use the QBO time series to analyse atmospheric data sets (reconstructions and reanalyses) as well as the results of coupled ocean-atmosphere-chemistry climate model simulations that were forced with the reconstructed QBO. We investigate effects related to (1) tropical-extratropical interaction in the stratosphere, wave-mean flow interaction and subsequent downward propagation, and (2) interaction between deep tropical convection and stratospheric flow. We generally find weak connections, though some are statistically significant over the 100-year period and consistent with model results. Apparent multidecadal variations in the connection between the QBO and the investigated climate responses are consistent with a small effect in the presence of large variability, with one exception: the imprint on the northern polar vortex, which is seen in recent reanalysis data, is not found in the period . Conversely, an imprint in Berlin surface air temperature is only found in but not in the recent period. Likewise, in the model simulations both links tend to appear alternatingly, suggesting a more systematic modulation due to a shift in the circulation, for example. Over the Pacific warm pool, we find increased convection during easterly QBO, mainly in boreal winter in observation-based data as well as in the model simulations, with large variability. No QBO effects were found in the Indian monsoon strength or Atlantic hurricane frequency.

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The Influence of the Quasi-Biennial Oscillation on the Troposphere in Winter in a Hierarchy of Models. Part II: Perpetual Winter WACCM Runs

Cited by 70 publications

References 41 publications

Stratospheric Response in the First Geoengineering Simulation Meeting Multiple Surface Climate Objectives

Stratospheric Response in the First Geoengineering Simulation Meeting Multiple Surface Climate Objectives

The Influence of the QBO on the Propagation of Equatorial Waves into the Stratosphere

Multidecadal variations of the effects of the Quasi-Biennial Oscillation on the climate system

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