Modifications of the quasi‐biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer

Aquila, Valentina; Garfinkel, Chaim I.; Newman, Paul A.; Oman, Luke D.; Waugh, Darryn W.

doi:10.1002/2013gl058818

Cited by 106 publications

(178 citation statements)

References 44 publications

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“…CE changes the hydrological cycle Kravitz et al, 2013) due to different effects on top of the atmosphere (TOA) and surface radiation ). An impact of the warming in the stratosphere on stratospheric dynamics was discussed by Aquila et al (2014) who simulate changes of the quasibiennial circulation caused by sulfur injection. For an injection of 1.25 Tg(S) yr −1 the westerly phase of the QBO is prolonged in the lower stratosphere, and the oscillation vanishes with the injection of 2.5 Tg(S) yr −1 .…”

Section: Introductionmentioning

confidence: 99%

“…The impact of sulfur injections on the QBO should, therefore, also affect transport processes in the stratosphere in addition to the acceleration of the Brewer-Dobson Circulation (BDC) described by Aquila et al (2014). The main intention of our study is to determine how changes of the transport of sulfate aerosol in the stratosphere are dependent on the state of the QBO and the jets in the tropical stratosphere.…”

Section: Introductionmentioning

confidence: 99%

“…We performed simulations with the General Circulation Model ECHAM5 (Roeckner et al, 2003) coupled to an aerosol microphysics model (HAM) (Stier et al, 2005). We attempt to answer the questions if ECHAM5-HAM simulates similar impacts on the QBO as described in Aquila et al (2014), and which consequences this has for dynamical processes in the stratosphere, the global distribution of sulfate aerosol, and the cooling efficiency of the artificial aerosol layer. Niemeier and Timmreck (2015) determined the efficiency of sulfur injections depending on injection rate and injection area.…”

Section: Introductionmentioning

confidence: 99%

“…However, their model could not generate a QBO. Aquila et al (2014) showed an intensification of the equatorial jet caused by the impact of sulfur injections. One may hence expect that changing jets caused by stratospheric sulfate heating feeds back to the sulfate distribution.…”

Section: Introductionmentioning

confidence: 99%

“…This paper is structured as follows: We give a brief general overview of stratospheric dynamics and the QBO (Sect. 2) and summarize the explanation given by Aquila et al (2014) of how the heated sulfate layer impacts the QBO. The model setup and the simulations performed in this work are described in Sect.…”

Section: Introductionmentioning

confidence: 99%

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Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

2017

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Abstract. The injection of sulfur dioxide (SO 2 ) into the stratosphere to form an artificial stratospheric aerosol layer is discussed as an option for solar radiation management. Sulfate aerosol scatters solar radiation and absorbs infrared radiation, which warms the stratospheric sulfur layer. Simulations with the general circulation model ECHAM5-HAM, including aerosol microphysics, show consequences of this warming, including changes of the quasi-biennial oscillation (QBO) in the tropics. The QBO slows down after an injection of 4 Tg(S) yr −1 and completely shuts down after an injection of 8 Tg(S) yr −1 . Transport of species in the tropics and subtropics depends on the phase of the QBO. Consequently, the heated aerosol layer not only impacts the oscillation of the QBO but also the meridional transport of the sulfate aerosols. The stronger the injection, the stronger the heating and the simulated impact on the QBO and equatorial wind systems. With increasing injection rate the velocity of the equatorial jet streams increases, and the less sulfate is transported out of the tropics. This reduces the global distribution of sulfate and decreases the radiative forcing efficiency of the aerosol layer by 10 to 14 % compared to simulations with low vertical resolution and without generated QBO. Increasing the height of the injection increases the radiative forcing only for injection rates below 10 Tg(S) yr −1 (8-18 %), a much smaller value than the 50 % calculated previously. Stronger injection rates at higher levels even result in smaller forcing than the injections at lower levels.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

2017

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Contributions of equatorial wave modes and parameterized gravity waves to the tropical QBO in HadGEM2

Kim

Chun

2015

JGR Atmospheres

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The contributions of the equatorial waves to the quasi-biennial oscillation (QBO) are investigated using Hadley Centre Global Environment Model version 2 (HadGEM2). A gravity wave parameterization that couples its source spectrum to the convection is used. The equatorial wave modes are identified in the spectral domain, based on their distinct characteristics associated with momentum and heat fluxes. The Kelvin waves and parameterized gravity waves (PGWs) transport westerly momentum into the equatorial stratosphere by ∼0.35 and 0.8 mPa, respectively, while easterly momentum is carried primarily by the PGWs (∼0.75 mPa). The resolved inertio-gravity (IG) waves transport both easterly and westerly momentum by ∼0.2 mPa. In the lowermost stratosphere, gradual dissipation of the Kelvin waves occurs, and the remaining waves induce eastward forcing in the westerly shear layer by 3-5 m s −1 month −1 . The PGWs primarily dissipate within the sheared layer and provide large easterly and westerly forcing in the middle stratosphere (∼17 m s −1 month −1 ), while the forcing in the lower stratosphere is comparable to the Kelvin wave forcing. The IG wave forcing is small because of the small wave dissipation rate. The Rossby and mixed Rossby-gravity (MRG) waves contribute to the westerly-to-easterly QBO transition by ∼2 m s −1 month −1 . The magnitudes of the simulated Kelvin and Rossby wave forcings are comparable with the Modern-Era Retrospective Analysis for Research and Applications, whereas the MRG and IG wave forcings are underestimated in the lower stratosphere. Differences between the simulation and reanalysis and the uncertainties in both are discussed.

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Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC

et al. 2015

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Multiyear simulations with the atmospheric chemistry general circulation model EMAC with a microphysical modal aerosol module at high vertical resolution demonstrate that the sulfur gases COS and SO2, the latter from low-latitude and midlatitude volcanic eruptions, predominantly control the formation of stratospheric aerosol. Marine dimethyl sulfide (DMS) and other SO2 sources, including strong anthropogenic emissions in China, are found to play a minor role except in the lowermost stratosphere. Estimates of volcanic SO2 emissions are based on satellite observations using Total Ozone Mapping Spectrometer and Ozone Monitoring Instrument for total injected mass and Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat or Stratospheric Aerosol and Gases Experiment for the spatial distribution. The 10 year SO2 and COS data set of MIPAS is also used for model evaluation. The calculated radiative forcing of stratospheric background aerosol including sulfate from COS and small contributions by DMS oxidation, and organic aerosol from biomass burning, is about 0.07W/m2. For stratospheric sulfate aerosol from medium and small volcanic eruptions between 2005 and 2011 a global radiative forcing up to 0.2W/m2 is calculated, moderating climate warming, while for the major Pinatubo eruption the simulated forcing reaches 5W/m2, leading to temporary climate cooling. The Pinatubo simulation demonstrates the importance of radiative feedback on dynamics, e.g., enhanced tropical upwelling, for large volcanic eruptions.

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Modifications of the quasi‐biennial oscillation by a geoengineering perturbation of the stratospheric aerosol layer

Cited by 106 publications

References 44 publications

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

Contributions of equatorial wave modes and parameterized gravity waves to the tropical QBO in HadGEM2

Stratospheric sulfur and its implications for radiative forcing simulated by the chemistry climate model EMAC

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