The impact of volcanic aerosol on the Northern Hemisphere stratospheric polar vortex: mechanisms and sensitivity to forcing structure

Toohey, Matthew; Krüger, Kirstin; Bittner, Matthias; Timmreck, Claudia; Schmidt, Hauke

doi:10.5194/acp-14-13063-2014

Cited by 71 publications

(112 citation statements)

References 44 publications

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“…A more detailed analysis of dynamical consequences including enhanced wave activity is presented by Toohey et al [2014]. Ignoring the radiative feedback on dynamics would reduce the aerosol extinction in the upper part of the volcanic aerosol plume (28 km in September 1991 descending to 24 km 1 year later) by more than 50% as shown by a sensitivity simulation.…”

Section: Feedback On Dynamicsmentioning

confidence: 98%

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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Section: Feedback On Dynamicsmentioning

confidence: 98%

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

et al. 2015

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“…It amplifies the Brewer-Dobson circulation (BDC) and modifies the equator-to-pole temperature gradient, driving changes in geostrophic zonal winds and the propagation of atmospheric waves (e.g. Bittner et al, 2016;Toohey et al, 2014) and strengthening the polar vortex (e.g. Charlton-Perez et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP): motivation and experimental design

et al. 2018

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Abstract. The Stratospheric Sulfur and its Role in Climate (SSiRC) Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP) explores uncertainties in the processes that connect volcanic emission of sulfur gas species and the radiative forcing associated with the resulting enhancement of the stratospheric aerosol layer. The central aim of ISA-MIP is to constrain and improve interactive stratospheric aerosol models and reduce uncertainties in the stratospheric aerosol forcing by comparing results of standardized model experiments with a range of observations. In this paper we present four co-ordinated inter-model experiments designed to investigate key processes which influence the formation and temporal development of stratospheric aerosol in different time periods of the observational record. The Background (BG) experiment will focus on microphysics and transport processes under volcanically quiescent conditions, when the stratospheric aerosol is controlled by the transport of aerosols and their precursors from the troposphere to the stratosphere. The Transient Aerosol Record (TAR) experiment will explore the role of small-to moderate-magnitude volcanic eruptions, anthropogenic sulfur emissions, and transport processes over the period 1998-2012 and their role in the warming hiatus. Two further experiments will investigate the stratospheric sulfate aerosol evolution after major volcanic eruptions. The Historical Eruptions SO 2 Emission Assessment (HErSEA) experiment will focus on the uncertainty in the initial emission of recent large-magnitude volcanic eruptions, while the Pinatubo Em-

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“…A consequence is a reduction of the equator to pole temperature gradient in the upper stratosphere, and an increase of the gradient in the lower stratosphere. The temperature anomalies in the upper stratosphere, including the cooling above the heated aerosol layer in the tropics, are caused by the increase of the residual vertical wind, vertical advection, and the related adiabatic heating anomalies (Toohey et al, 2014).…”

Section: Effects On Stratospheric Temperaturementioning

confidence: 99%

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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The impact of volcanic aerosol on the Northern Hemisphere stratospheric polar vortex: mechanisms and sensitivity to forcing structure

Cited by 71 publications

References 44 publications

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

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

The Interactive Stratospheric Aerosol Model Intercomparison Project (ISA-MIP): motivation and experimental design

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

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