Volcanic aerosols and interannual variation of high clouds

Song, Naihui; Starr, David Oc.; Wuebbles, Donald J.; Williams, A.; Larson, Susan M.

doi:10.1029/96gl02372

Cited by 23 publications

(15 citation statements)

References 24 publications

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“…Song et al [] analyzed outgoing longwave radiation data from the NOAA Climate Analysis Center and SAGE II and ground‐based lidar observations. They found high‐level cloudiness to increase with the global stratospheric aerosol load, particularly in the midlatitudes, and concluded that volcanic aerosol can significantly modify high‐level cloudiness and thereby affect global climate.…”

Section: Potential Effects Of Volcanic Aerosols On Ice Cloudssupporting

confidence: 80%

Did the 2011 Nabro eruption affect the optical properties of ice clouds?

et al. 2015

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The eruption of the Eritrean Nabro Volcano in June 2011 was the largest eruption since Mount Pinatubo in June 1991. The Nabro volcano emitted 1-1.5 megaton of sulfur dioxide into the lower stratosphere which resulted in a significant rise in the stratospheric sulfate aerosol burden in the months following the eruption. We have analyzed backscatter and extinction from ice clouds, as measured by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite between June 2006 and May 2014, to assess if volcanic aerosol produced by the Nabro eruption had affected ice clouds. We found no significant modifications of either of ice cloud optical properties (i.e., total backscattering and extinction), occurrence frequencies, or residence altitudes on a global scale. Using the analyzed optical properties as indicators of posteruptive ice cloud radiative forcing modifications, we find that the eruption had no significant volcanic aerosol-ice cloud radiative effect. Our results suggest that the investigated optical properties of ice and cirrus clouds are at most weakly dependent on the sulfate droplet number density and size distribution.

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Section: Potential Effects Of Volcanic Aerosols On Ice Cloudssupporting

confidence: 80%

Did the 2011 Nabro eruption affect the optical properties of ice clouds?

et al. 2015

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“…However, other observational analyses have failed to find a connection between Pinatubo and cirrus (Luo et al, 1997). It is possible that El Niño contributed to the change in cirrus properties that year (Song et al, 1996), but other analyses suggest El Niño was insignificant compared to the effects of Mt. Pinatubo (Wang et al, 1995).…”

Section: Tropospheric Burdensmentioning

confidence: 88%

Microphysical simulations of sulfur burdens from stratospheric sulfur geoengineering

2012

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Abstract. Recent microphysical studies suggest that geoengineering by continuous stratospheric injection of SO 2 gas may be limited by the growth of the aerosols. We study the efficacy of SO 2 , H 2 SO 4 and aerosol injections on aerosol mass and optical depth using a three-dimensional general circulation model with sulfur chemistry and sectional aerosol microphysics (WACCM/CARMA). We find increasing injection rates of SO 2 in a narrow band around the equator to have limited efficacy while broadening the injecting zone as well as injecting particles instead of SO 2 gas increases the sulfate burden for a given injection rate, in agreement with previous work. We find that injecting H 2 SO 4 gas instead of SO 2 does not discernibly alter sulfate size or mass, in contrast with a previous study using a plume model with a microphysical model. However, the physics and chemistry in aircraft plumes, which are smaller than climate model grid cells, need to be more carefully considered. We also find significant perturbations to tropospheric aerosol for all injections studied, particularly in the upper troposphere and near the poles, where sulfate burden increases by up to 100 times. This enhanced burden could have implications for tropospheric radiative forcing and chemistry. These results highlight the need to mitigate greenhouse gas emissions rather than attempt to cool the planet through geoengineering, and to further study geoengineering before it can be seriously considered as a climate intervention option.

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“…In this way, they may also represent an indirect significant perturbation in the longwave radiation balance. A correlation between UT ice clouds and explosive volcanic eruptions has been reported in Song et al [21]. A more recent study by Kärcher and Lohmann [22] shows that the UT formation of ice crystals is dominated by homogeneous freezing of solution droplets below temperatures of approximately 233 K. This physical mechanism is primarily driven by UT temperatures and vertical velocities of adiabatically rising air parcels with higher water vapor content; the aerosol size distribution plays only a minor role.…”

Section: Introductionmentioning

confidence: 90%

Sulfate Aerosols from Non-Explosive Volcanoes: Chemical-Radiative Effects in the Troposphere and Lower Stratosphere

et al. 2016

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SO 2 and H 2 S are the two most important gas-phase sulfur species emitted by volcanoes, with a global amount from non-explosive emissions of the order 10 Tg-S/yr. These gases are readily oxidized forming SO 4 2´a erosols, which effectively scatter the incoming solar radiation and cool the surface. They also perturb atmospheric chemistry by enhancing the NO x to HNO 3 heterogeneous conversion via hydrolysis on the aerosol surface of N 2 O 5 and Br-Cl nitrates. This reduces formation of tropospheric O 3 and the OH to HO 2 ratio, thus limiting the oxidation of CH 4 and increasing its lifetime. In addition to this tropospheric chemistry perturbation, there is also an impact on the NO x heterogeneous chemistry in the lower stratosphere, due to vertical transport of volcanic SO 2 up to the tropical tropopause layer. Furthermore, the stratospheric O 3 formation and loss, as well as the NO x budget, may be slightly affected by the additional amount of upward diffused solar radiation and consequent increase of photolysis rates. Two multi-decadal time-slice runs of a climate-chemistry-aerosol model have been designed for studying these chemical-radiative effects. A tropopause mean global net radiative flux change (RF) of´0.23 W¨m´2 is calculated (including direct and indirect aerosol effects) with a 14% increase of the global mean sulfate aerosol optical depth. A 5-15 ppt NO x decrease is found in the mid-troposphere subtropics and mid-latitudes and also from pole to pole in the lower stratosphere. The tropospheric NO x perturbation triggers a column O 3 decrease of 0.5-1.5 DU and a 1.1% increase of the CH 4 lifetime. The surface cooling induced by solar radiation scattering by the volcanic aerosols induces a tropospheric stabilization with reduced updraft velocities that produce ice supersaturation conditions in the upper troposphere. A global mean 0.9% decrease of the cirrus ice optical depth is calculated with an indirect RF of´0.08 W¨m´2.

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Volcanic aerosols and interannual variation of high clouds

Cited by 23 publications

References 24 publications

Did the 2011 Nabro eruption affect the optical properties of ice clouds?

Did the 2011 Nabro eruption affect the optical properties of ice clouds?

Microphysical simulations of sulfur burdens from stratospheric sulfur geoengineering

Sulfate Aerosols from Non-Explosive Volcanoes: Chemical-Radiative Effects in the Troposphere and Lower Stratosphere

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