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Columnar optical, microphysical and radiative properties of the 2022 Hunga Tonga volcanic ash plumes. Sci Bull (Beijing) 2022; 67:2013-2021. [DOI: 10.1016/j.scib.2022.08.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 07/03/2022] [Accepted: 07/04/2022] [Indexed: 11/22/2022]
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McGrory MR, Shepherd RH, King MD, Davidson N, Pope FD, Watson IM, Grainger RG, Jones AC, Ward AD. Mie scattering from optically levitated mixed sulfuric acid-silica core-shell aerosols: observation of core-shell morphology for atmospheric science. Phys Chem Chem Phys 2022; 24:5813-5822. [PMID: 35226003 DOI: 10.1039/d1cp04068e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sulfuric acid is shown to form a core-shell particle on a micron-sized, optically-trapped spherical silica bead. The refractive indices of the silica and sulfuric acid, along with the shell thickness and bead radius were determined by reproducing Mie scattered optical white light as a function of wavelength in Mie spectroscopy. Micron-sized silica aerosols (silica beads were used as a proxy for atmospheric silica minerals) were levitated in a mist of sulfuric acid particles; continuous collection of Mie spectra throughout the collision of sulfuric acid aerosols with the optically trapped silica aerosol demonstrated that the resulting aerosol particle had a core-shell morphology. Contrastingly, the collision of aqueous sulfuric acid aerosols with optically trapped polystyrene aerosol resulted in a partially coated system. The light scattering from the optically levitated aerosols was successfully modelled to determine the diameter of the core aerosol (±0.003 μm), the shell thickness (±0.0003 μm) and the refractive index (±0.007). The experiment demonstrated that the presence of a thin film rapidly changed the light scattering of the original aerosol. When a 1.964 μm diameter silica aerosol was covered with a film of sulfuric acid 0.287 μm thick, the wavelength dependent Mie peak positions resembled sulfuric acid. Thus mineral aerosol advected into the stratosphere would likely be coated with sulfuric acid, with a core-shell morphology, and its light scattering properties would be effectively indistinguishable from a homogenous sulfuric acid aerosol if the film thickness was greater than a few 100 s of nm for UV-visible wavelengths.
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Affiliation(s)
- Megan R McGrory
- Central Laser Facility, Research Complex, STFC Rutherford Appleton Laboratory, Oxford, OX11 0FA, UK. .,Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK
| | - Rosalie H Shepherd
- Central Laser Facility, Research Complex, STFC Rutherford Appleton Laboratory, Oxford, OX11 0FA, UK. .,Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK
| | - Martin D King
- Department of Earth Sciences, Royal Holloway, University of London, Egham, Surrey, TW20 0EX, UK
| | - Nicholas Davidson
- School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - Francis D Pope
- School of Geography, Earth & Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK
| | - I Matthew Watson
- School of Earth Science, University of Bristol, Wills Memorial Building, Bristol, BS8 1RJ, UK
| | - Roy G Grainger
- National Centre for Earth Observation, Atmospheric, Oceanic and Planetary Physics, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Anthony C Jones
- Met Office, Fitzroy Road, Exeter, EX1 3PB, UK.,College of Engineering Maths and Physical Sciences, University of Exeter, Exeter, EX4 4PY, UK
| | - Andrew D Ward
- Central Laser Facility, Research Complex, STFC Rutherford Appleton Laboratory, Oxford, OX11 0FA, UK.
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Variability of the Aerosol Content in the Tropical Lower Stratosphere from 2013 to 2019: Evidence of Volcanic Eruption Impacts. ATMOSPHERE 2022. [DOI: 10.3390/atmos13020250] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This paper quantifies the tropical stratospheric aerosol content as impacted by volcanic events over the 2013–2019 period. We use global model simulations by the Whole Atmosphere Community Climate Model (WACCM) which is part of the Community Earth System Model version 1.0 (CESM1). WACCM is associated with the Community Aerosol and Radiation Model for Atmospheres (CARMA) sectional aerosol microphysics model which includes full sulphur chemical and microphysical cycles with no a priori assumption on particle size. Five main volcanic events (Kelud, Calbuco, Ambae, Raikoke and Ulawun) have been reported and are shown to have significantly influenced the stratospheric aerosol layer in the tropics, either through direct injection in this region or through transport from extra-tropical latitudes. Space-borne data as well as ground-based lidar and balloon-borne in situ observations are used to evaluate the model calculations in terms of aerosol content, vertical distribution, optical and microphysical properties, transport and residence time of the various volcanic plumes. Overall, zonal mean model results reproduce the occurrence and vertical extents of the plumes derived from satellite observations but shows some discrepancies for absolute values of extinction and of stratospheric aerosol optical depth (SAOD). Features of meridional transport of the plumes emitted from extra-tropical latitudes are captured by the model but simulated absolute values of SAOD differ from 6 to 200% among the various eruptions. Simulations tend to agree well with observed in situ vertical profiles for the Kelud and Calbuco plumes but this is likely to depend on the period for which comparison is done. Some explanations for the model–measurement discrepancies are discussed such as the inaccurate knowledge of the injection parameters and the presence of ash not accounted in the simulations.
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Fadnavis S, Müller R, Chakraborty T, Sabin TP, Laakso A, Rap A, Griessbach S, Vernier JP, Tilmes S. The role of tropical volcanic eruptions in exacerbating Indian droughts. Sci Rep 2021; 11:2714. [PMID: 33526810 PMCID: PMC7851170 DOI: 10.1038/s41598-021-81566-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 01/06/2021] [Indexed: 01/30/2023] Open
Abstract
The Indian summer monsoon rainfall (ISMR) is vital for the livelihood of millions of people in the Indian region; droughts caused by monsoon failures often resulted in famines. Large volcanic eruptions have been linked with reductions in ISMR, but the responsible mechanisms remain unclear. Here, using 145-year (1871-2016) records of volcanic eruptions and ISMR, we show that ISMR deficits prevail for two years after moderate and large (VEI > 3) tropical volcanic eruptions; this is not the case for extra-tropical eruptions. Moreover, tropical volcanic eruptions strengthen El Niño and weaken La Niña conditions, further enhancing Indian droughts. Using climate-model simulations of the 2011 Nabro volcanic eruption, we show that eruption induced an El Niño like warming in the central Pacific for two consecutive years due to Kelvin wave dissipation triggered by the eruption. This El Niño like warming in the central Pacific led to a precipitation reduction in the Indian region. In addition, solar dimming caused by the volcanic plume in 2011 reduced Indian rainfall.
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Affiliation(s)
| | - Rolf Müller
- Forschungszentrum Jülich GmbH, IEK7, Jülich, Germany
| | | | - T P Sabin
- Indian Institute of Tropical Meteorology, MoES, Pune, India
| | - Anton Laakso
- Finnish Meteorological Institute, Kuopio, Finland
| | - Alexandru Rap
- School of Earth and Environment, University of Leeds, Leeds, UK
| | - Sabine Griessbach
- Forschungszentrum Jülich GmbH, Jülich Supercomputing Center, Jülich, Germany
| | - Jean-Paul Vernier
- National Institute of Aerospace, Hampton, VA, USA
- NASA Langley Research Center, Hampton, VA, USA
| | - Simone Tilmes
- National Center for Atmospheric Research, Boulder, USA
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MacMartin DG, Ricke KL, Keith DW. Solar geoengineering as part of an overall strategy for meeting the 1.5°C Paris target. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20160454. [PMID: 29610384 PMCID: PMC5897825 DOI: 10.1098/rsta.2016.0454] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 10/16/2017] [Indexed: 05/15/2023]
Abstract
Solar geoengineering refers to deliberately reducing net radiative forcing by reflecting some sunlight back to space, in order to reduce anthropogenic climate changes; a possible such approach would be adding aerosols to the stratosphere. If future mitigation proves insufficient to limit the rise in global mean temperature to less than 1.5°C above preindustrial, it is plausible that some additional and limited deployment of solar geoengineering could reduce climate damages. That is, these approaches could eventually be considered as part of an overall strategy to manage the risks of climate change, combining emissions reduction, net-negative emissions technologies and solar geoengineering to meet climate goals. We first provide a physical-science review of current research, research trends and some of the key gaps in knowledge that would need to be addressed to support informed decisions. Next, since few climate model simulations have considered these limited-deployment scenarios, we synthesize prior results to assess the projected response if solar geoengineering were used to limit global mean temperature to 1.5°C above preindustrial in an overshoot scenario that would otherwise peak near 3°C. While there are some important differences, the resulting climate is closer in many respects to a climate where the 1.5°C target is achieved through mitigation alone than either is to the 3°C climate with no geoengineering. This holds for both regional temperature and precipitation changes; indeed, there are no regions where a majority of models project that this moderate level of geoengineering would produce a statistically significant shift in precipitation further away from preindustrial levels.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.
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Affiliation(s)
- Douglas G MacMartin
- Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14850, USA
| | - Katharine L Ricke
- Scripps Institution of Oceanography and School of Global Policy and Strategy, University of California, San Diego, CA, USA
| | - David W Keith
- John A. Paulson School of Engineering and Applied Sciences and John F. Kennedy School of Government, Harvard University, Cambridge, MA, USA
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