Modulation of Antarctic vortex composition by the quasi‐biennial oscillation

Strahan, S. E.; Oman, Luke D.; Douglass, Anne R.; Coy, L.

doi:10.1002/2015gl063759

Cited by 45 publications

(55 citation statements)

References 41 publications

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“…QBO-driven column O 3 anomalies originating in the southern subtropics in early winter reach 60 • S by the early spring (Gray and Ruth, 1993;Randel and Wu, 1996;Kinnersley and Tung, 1998). Strahan et al (2015) also showed a transport pathway by which the midlatitude middle-stratosphere QBO signal affects polar O 3 depletion by modulating Antarctic inorganic chlorine.…”

Section: Introductionmentioning

confidence: 88%

Response of trace gases to the disrupted 2015–2016 quasi-biennial oscillation

et al. 2017

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Abstract. The quasi-biennial oscillation (QBO) is a quasiperiodic alternation between easterly and westerly zonal winds in the tropical stratosphere, propagating downward from the middle stratosphere to the tropopause with a period that varies from 24 to 32 months ( ∼ 28 months on average). The QBO wind oscillations affect the distribution of chemical constituents, such as ozone (O 3 ), water vapor (H 2 O), nitrous oxide (N 2 O), and hydrochloric acid (HCl), through the QBO-induced meridional circulation. In the 2015-2016 winter, radiosonde observations revealed an anomaly in the downward propagation of the westerly phase, which was disrupted by the upward displacement of the westerly phase from ∼ 30 hPa up to 15 hPa and the sudden appearance of easterlies at 40 hPa. Such a disruption is unprecedented in the observational record from 1953 to the present. In this study we show the response of trace gases to this QBO disruption using O 3 , HCl, H 2 O, and temperature from the Aura Microwave Limb Sounder (MLS) and total ozone measurements from the Solar Backscatter Ultraviolet (SBUV) Merged Ozone Data Set (MOD). Results reveal the development of positive anomalies in stratospheric equatorial O 3 and HCl over ∼ 50-30 hPa in May-September of 2016 and a substantial decrease in O 3 in the subtropics of both hemispheres. The SBUV observations show near-record low levels of column ozone in the subtropics in 2016, resulting in an increase in the surface UV index during northern summer. Furthermore, cold temperature anomalies near the tropical tropopause result in a global decrease in stratospheric water vapor.

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Section: Introductionmentioning

confidence: 88%

Response of trace gases to the disrupted 2015–2016 quasi-biennial oscillation

et al. 2017

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“…3.1.2.). In contrast, methane over Arrival Heights shows high variability from one year to another, which illustrates how dynamically sensitive the polar air is to transport from lower latitudes (Strahan et al, 2015).…”

Section: Tagged Simulation Analysismentioning

confidence: 98%

The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005

Bader

Bovy²,

Conway

et al. 2017

Atmos. Chem. Phys.

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Abstract. Changes of atmospheric methane total columns (CH 4 ) since 2005 have been evaluated using Fourier transform infrared (FTIR) solar observations carried out at 10 ground-based sites, affiliated to the Network for Detection of Atmospheric Composition Change (NDACC). From this, we find an increase of atmospheric methane total columns of 0.31 ± 0.03 % year −1 (2σ level of uncertainty) for the 2005-2014 period. Comparisons with in situ methane measurements at both local and global scales show good agreement. We used the GEOS-Chem chemical transport model tagged simulation, which accounts for the contribution of each emission source and one sink in the total methane, simulated over 2005-2012. After regridding according to NDACC vertical layering using a conservative regridding scheme and smoothing by convolving with respective FTIR seasonal averaging kernels, the GEOS-Chem simulation shows an increase of atmospheric methane total columns of 0.35 ± 0.03 % year −1 between 2005 and 2012, which is in agreement with NDACC measurements over the same time period (0.30 ± 0.04 % year −1 , averaged over 10 stations). Analysis of the GEOS-Chem-tagged simulation allows us to quantify the contribution of each tracer to the global methane change since 2005. We find that natural sources such as wetlands and biomass burning contribute to the interannual variability of methane. However, anthropogenic emissions, such as coal mining, and gas and oil transport and exploration, which are mainly emitted in the Northern Hemisphere and act as secondary contributors to the global budget of methane, have played a major role in the increase of atmospheric methane observed since 2005. Based on the GEOSPublished by Copernicus Publications on behalf of the European Geosciences Union. W. Bader et al.: The recent increase of atmospheric methaneChem-tagged simulation, we discuss possible cause(s) for the increase of methane since 2005, which is still unexplained.

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“…This is an essential prerequisite to improving the representation in models of important QBO influences (Baldwin et al, 2001), such as the modulation of the transport of aerosols and chemical constituents into and within the stratosphere (e.g. Strahan et al, 2015) or the dynamical teleconnections to the extra-tropics (Anstey and Shepherd, 2014), and their subsequent surface climate and weather impacts. These aspects are expected to be included more prominently in the next phase of QBOi.…”

Section: Introductionmentioning

confidence: 99%

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

Anstey²,

et al. 2018

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Abstract. The Stratosphere-troposphere Processes And their Role in Climate (SPARC) Quasi-Biennial Oscillation initiative (QBOi) aims to improve the fidelity of tropical stratospheric variability in general circulation and Earth system models by conducting coordinated numerical experiments and analysis. In the equatorial stratosphere, the QBO is the most conspicuous mode of variability. Five coordinated experiments have therefore been designed to (i) evaluate and compare the verisimilitude of modelled QBOs under presentday conditions, (ii) identify robustness (or alternatively the spread and uncertainty) in the simulated QBO response to commonly imposed changes in model climate forcings (e.g. a doubling of CO 2 amounts), and (iii) examine model dependence of QBO predictability. This paper documents these experiments and the recommended output diagnostics. The rationale behind the experimental design and choice of diagnostics is presented. To facilitate scientific interpretation of the results in other planned QBOi studies, consistent descriptions of the models performing each experiment set are given, with those aspects particularly relevant for simulating the QBO tabulated for easy comparison.

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Modulation of Antarctic vortex composition by the quasi‐biennial oscillation

Cited by 45 publications

References 41 publications

Response of trace gases to the disrupted 2015–2016 quasi-biennial oscillation

Response of trace gases to the disrupted 2015–2016 quasi-biennial oscillation

The recent increase of atmospheric methane from 10 years of ground-based NDACC FTIR observations since 2005

Overview of experiment design and comparison of models participating in phase 1 of the SPARC Quasi-Biennial Oscillation initiative (QBOi)

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