Particles Above the Tropopause: Measurements and Models of Stratospheric Aerosols, Meteoric Debris, Nacreous Clouds, and Noctilucent Clouds

Toon, O. B.; Farlow, N. H.

doi:10.1146/annurev.ea.09.050181.000315

Cited by 41 publications

(15 citation statements)

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“…OC has different optical properties compared to BC: while BC particles absorb sunlight and reduce the planetary albedo, OC particles have a much lower absorption coefficient and generally scatter solar radiation. When co-emitted OC can coagulate with BC, increasing BC absorption by ∼50% [Toon and Farlow, 1981;Toon et al, 2007b]. However, BC/OC coagulation also leads to a larger particle size, which most likely will reduce the residence time of the particles.…”

Section: 1002/2016ef000415mentioning

confidence: 99%

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

et al. 2016

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Here, we use a coupled atmospheric-ocean-aerosol model to investigate the plume development and climate effects of the smoke generated by fires following a regional nuclear war between emerging third-world nuclear powers. We simulate a standard scenario where 5 Tg of black carbon (BC) is emitted over 1 day in the upper troposphere-lower stratosphere. However, it is likely that the emissions from the fires ignited by bomb detonations include a substantial amount of particulate organic matter (POM) and that they last more than 1 day. We therefore test the sensitivity of the aerosol plume and climate system to the BC/POM ratio (1:3, 1:9) and to the emission length (1 day, 1 week, 1 month). We find that in general, an emission length of 1 month substantially reduces the cooling compared to the 1-day case, whereas taking into account POM emissions notably increases the cooling and the reduction of precipitation associated with the nuclear war during the first year following the detonation. Accounting for POM emissions increases the particle size in the short-emission-length scenarios (1 day/1 week), reducing the residence time of the injected particle. While the initial cooling is more intense when including POM emission, the long-lasting effects, while still large, may be less extreme compared to the BC-only case. Our study highlights that the emission altitude reached by the plume is sensitive to both the particle type emitted by the fires and the emission duration. Consequently, the climate effects of a nuclear war are strongly dependent on these parameters.

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Section: 1002/2016ef000415mentioning

confidence: 99%

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

et al. 2016

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“…In the previous study by Brown [1999], the lifetime against coagulation was taken as [Toon and Farlow, 1981] T c ---106/(NF 1/2)…”

Section: C3h8 + O(1d) -• C3h7 + Oh C3h8 + Oh -• C3h7 + H20 Ch2co + H mentioning

confidence: 99%

UV shielding of NH₃and O₂by organic hazes in the Archean atmosphere

Pavlov¹,

Brown²,

Kasting³

2001

J. Geophys. Res.

255

258

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Abstract. The late Archean atmosphere was probably rich in biologically generated CH4 and may well have contained a hydrocarbon haze layer similar to that observed today on Satum's moon, Titan. Here we present a detailed model of the photochemistry of haze formation in the early atmosphere, and we examine the effects of such a haze layer on climate and ultraviolet radiation. We show that the thickness of the haze layer was limited by a negative feedback loop: A haze optical depth of more than •0.5 in the visible would have produced a strong "antigreenhouse effect," thereby cooling the surface and slowing the rate at which CH 4 was produced. Given this climatic constraint on its visible optical depth, the amount of UV shielding provided by the haze can be estimated from knowledge of the optical properties and size distribution of the haze particles. Contrary to previous studies [Sagan and Chyba, 1997], we find that when the finite size of the particles is taken into account, the amount of UV shielding provided by the haze is small. Thus NH3 should have been rapidly photolyzed and should not have been sufficiently abundant to augment the atmospheric greenhouse effect. We also examine the question of whether photosynthetically generated 02 could have accumulated beneath the haze layer. For the model parameters considered here, the answer is "no": The upper limit on ground level 02 concentrations is • 10 -6 atm, and a more realistic estimate for pO2 during the late Archean is 10 -8 atm. The stability of both 02 and NH3 is sensitive to the size distribution and optical properties of the haze particles, neither of which is well known. Further theoretical and laboratory work is needed to address these uncertainties.

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“…The lower stratosphere contains higher mass concentrations of aerosol particles than higher or lower altitudes. The number, size and optical properties of stratospheric aerosols were reviewed by Cadle and Grams (1975), Toon and Farlow (1981), Turco et al (1982), Thomason and Peter (2006) and Deshler (2008), but the chemical composition of stratospheric aerosols has not been extensively reviewed.…”

Section: Introductionmentioning

confidence: 99%

“…The chemical form of the sulphate was not immediately known (Toon and Farlow, 1981). Ammonium sulphate (Junge and Manson, 1961), sulphuric acid and even other sulphur compounds were considered (Bigg et al, 1970).…”

Section: Introductionmentioning

confidence: 99%

Observations of the chemical composition of stratospheric aerosol particles

Murphy

Froyd

Schwarz

et al. 2013

Quart J Royal Meteoro Soc

113

106

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Recent instrumentation can distinguish various types of aerosol particles in the stratosphere and determine their relative abundance. In the background lower stratosphere between major volcanic eruptions, most particles are either relatively pure sulphuric acid, sulphuric acid with material from ablated meteoroids or mixed organic-sulphate particles that originated in the troposphere. The meteoritic iron and magnesium appear to be dissolved whereas the aluminum and silicon appear to be inclusions. Most stratospheric aerosol mass is liquid sulphuric acid and associated water, but a large fraction of particles contain either inclusions of meteoritic elements such as silicon or organic material that is probably effloresced or glassy. These solid phases could have large but unknown implications for the ability of particles to act as freezing nuclei for polar stratospheric clouds. Internally mixed black carbon is a measurable but very small component of the stratospheric aerosol by mass. Despite their importance for heterogeneous chemistry, there are few quantitative measurements of halogens in stratospheric particles.

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Particles Above the Tropopause: Measurements and Models of Stratospheric Aerosols, Meteoric Debris, Nacreous Clouds, and Noctilucent Clouds

Cited by 41 publications

References 0 publications

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

UV shielding of NH₃and O₂by organic hazes in the Archean atmosphere

Observations of the chemical composition of stratospheric aerosol particles

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Particles Above the Tropopause: Measurements and Models of Stratospheric Aerosols, Meteoric Debris, Nacreous Clouds, and Noctilucent Clouds

Cited by 41 publications

References 0 publications

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

Climate effects of a hypothetical regional nuclear war: Sensitivity to emission duration and particle composition

UV shielding of NH3and O2by organic hazes in the Archean atmosphere

Observations of the chemical composition of stratospheric aerosol particles

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UV shielding of NH₃and O₂by organic hazes in the Archean atmosphere