Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport

Bourassa, Adam; Robock, Alan; Randel, William J.; Deshler, Terry; Rieger, Landon; Lloyd, Nicholas; Llewellyn, E. J.; Degenstein, D. A.

doi:10.1126/science.1219371

Cited by 214 publications

(244 citation statements)

References 26 publications

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“…Pinatubo (Bluth et al, 1992). The SO 2 was oxidised to sulfate aerosol and formed a stratospheric aerosol layer in the Northern Hemisphere (Bourassa et al, 2012;Sawamura et al, 2012). Due to the much smaller amount of SO 2 , for this event it is unlikely that the presented volcanic ash detection method would wrongly identify the sulfate aerosol layer as volcanic ash.…”

Section: Sulfate Aerosol Simulationsmentioning

confidence: 99%

Volcanic ash detection with infrared limb sounding: MIPAS observations and radiative transfer simulations

Grießbach¹,

Hoffmann²,

Spang³

et al. 2014

Atmos. Meas. Tech.

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Abstract. Small volcanic ash particles have long residence times in the troposphere and the stratosphere so that they have significant impact on the Earth's radiative budget and consequently affect climate. For global long-term observations of volcanic aerosol, infrared limb measurements provide excellent coverage, sensitivity to thin aerosol layers, and altitude information. The optical properties of volcanic ash and ice particles, derived from micro-physical properties, have opposing spectral gradients between 700 and 960 cm −1 for small particle sizes. Radiative transfer simulations that account for single scattering showed that the opposing spectral gradients directly transfer to infrared limb spectra. Indeed, we found the characteristic spectral signature, expected for volcanic ash, in measurements of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) after the eruption of the Chilean volcano Puyehue-Cordón Caulle in June 2011. From these measurements we derived an ash detection threshold function. The empirical ash detection threshold was confirmed in an extensive simulations study covering a wide range of atmospheric conditions, particle sizes and particle concentrations for ice, volcanic ash and sulfate aerosol. From the simulations we derived the upper detectable effective radius of 3.5 µm and the detectable extinction coefficient range of 5 × 10 −3 to 1 × 10 −1 km −1 . We also showed that this method is only sensitive to volcanic ash particles, but not to volcanic sulfate aerosol. This volcanic ash detection method for infrared limb measurements is a fast and reliable method and provides complementary information to existing satellite aerosol products.

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Section: Sulfate Aerosol Simulationsmentioning

confidence: 99%

Volcanic ash detection with infrared limb sounding: MIPAS observations and radiative transfer simulations

Grießbach¹,

Hoffmann²,

Spang³

et al. 2014

Atmos. Meas. Tech.

View full text Add to dashboard Cite

show abstract

“…It is plausible that gravitational instability in the mush is important in triggering eruption as suggested for eruptions of andesite magmas at Soufrière Hills volcano, Montserrat (Christopher et al 2015). Mush destabilisation can also lead to copious release of SO 2 gas previously stored at different levels, accounting for the large emission of SO 2 during the 2011 eruption of Nabro relative to the sulphur content that could have been contained within the erupted magma (Bourassa et al 2012).…”

Section: Magma Storage Depths and Plumbing System At Nabromentioning

confidence: 99%

The 2011 eruption of Nabro volcano, Eritrea: perspectives on magmatic processes from melt inclusions

Donovan

Blundy

Oppenheimer

et al. 2017

Contrib Mineral Petrol

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The 2011 eruption of Nabro volcano, Eritrea, produced one of the largest volcanic sulphur inputs to the atmosphere since the 1991 eruption of Mt. Pinatubo, yet has received comparatively little scientific attention. Nabro forms part of an off-axis alignment, broadly perpendicular to the Afar Rift, and has a history of large-magnitude explosive silicic eruptions, as well as smaller more mafic ones. Here, we present and analyse extensive petrological data obtained from samples of trachybasaltic tephra erupted during the 2011 eruption to assess the pre-eruptive magma storage system and explain the large sulphur emission. We show that the eruption involved two texturally distinct batches of magma, one of which was more primitive and richer in sulphur than the other, which was higher in water (up to 2.5 wt%). Modelling of the degassing and crystallisation histories demonstrates that the more primitive magma rose rapidly from depth and experienced degassing crystallisation, while the other experienced isobaric cooling in the crust at around 5 km depth. Interaction between the two batches occurred shortly before the eruption. The eruption itself was likely triggered by recharge-induced destabilisation of vertically extensive mush zone under the volcano. This could potentially account for the large volume of sulphur released. Some of the melt inclusions are volatile undersaturated, and suggest that the original water content of the magma was around 1.3 wt%, which is relatively high for an intraplate setting, but consistent with seismic studies of the Afar plume. This eruption was smaller than some geological eruptions at Nabro, but provides important insights into the plumbing systems and dynamics of off-axis volcanoes in Afar.

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“…1e). This increase in stratospheric aerosol loading is attributed to a number of small volcanic eruptions and anthropogenically released aerosols transported into the stratosphere during the Asian Monsoon (Bourassa et al, 2012;Neely et al, 2013). An aerosol data set has been constructed for the CCMI project (ftp://iacftp.ethz.ch/pub_read/ luo/ccmi/) and is similar to the data described by Solomon et al (2011).…”

Section: Forcings In Observations and Model Simulationsmentioning

confidence: 99%

Quantifying contributions to the recent temperature variability in the tropical tropopause layer

2015

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Abstract. The recently observed variability in the tropical tropopause layer (TTL), which features a warming of 0.9 K over the past decade (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011), is investigated with a number of sensitivity experiments from simulations with NCAR's CESM-WACCM chemistry-climate model. The experiments have been designed to specifically quantify the contributions from natural as well as anthropogenic factors, such as solar variability (Solar), sea surface temperatures (SSTs), the quasi-biennial oscillation (QBO), stratospheric aerosols (Aerosol), greenhouse gases (GHGs) and the dependence on the vertical resolution in the model. The results show that, in the TTL from 2001 through 2011, a cooling in tropical SSTs leads to a weakening of tropical upwelling around the tropical tropopause and hence relative downwelling and adiabatic warming of 0.3 K decade −1 ; stronger QBO westerlies result in a 0.2 K decade −1 warming; increasing aerosols in the lower stratosphere lead to a 0.2 K decade −1 warming; a prolonged solar minimum contributes about 0.2 K decade −1 to a cooling; and increased GHGs have no significant influence. Considering all the factors mentioned above, we compute a net 0.5 K decade −1 warming, which is less than the observed 0.9 K decade −1 warming over the past decade in the TTL. Two simulations with different vertical resolution show that, with higher vertical resolution, an extra 0.8 K decade −1 warming can be simulated through the last decade compared with results from the "standard" low vertical resolution simulation. Model results indicate that the recent warming in the TTL is partly caused by stratospheric aerosols and mainly due to internal variability, i.e. the QBO and tropical SSTs. The vertical resolution can also strongly influence the TTL temperature response in addition to variability in the QBO and SSTs.

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Large Volcanic Aerosol Load in the Stratosphere Linked to Asian Monsoon Transport

Cited by 214 publications

References 26 publications

Volcanic ash detection with infrared limb sounding: MIPAS observations and radiative transfer simulations

Volcanic ash detection with infrared limb sounding: MIPAS observations and radiative transfer simulations

The 2011 eruption of Nabro volcano, Eritrea: perspectives on magmatic processes from melt inclusions

Quantifying contributions to the recent temperature variability in the tropical tropopause layer

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