Formation and composition of the UTLS aerosol

Martinsson, Bengt G.; Friberg, Johan; Sandvik, Oscar S.; Hermann, M.; Velthoven, P. F. J. van; Zahn, Andreas

doi:10.1038/s41612-019-0097-1

Cited by 28 publications

(26 citation statements)

References 67 publications

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“…One important wavelength band is 200 to 242 nm, where photolysis of O 2 is responsible for formation of ozone and photolysis of N 2 O produces odd nitrogen (NO y ) (Brasseur and Solomon, 1986). For purely scattering particles, changes in photolysis in this wavelength range are reduced by large cancellations in direct and diffuse light (Michelangeli et al, 1989). Light scattering by the El Chichón volcanic cloud was estimated to reduce O 2 photolysis by about 10 % (Michelangeli et al, 1989).…”

Section: Ultraviolet Scattering and Absorptionmentioning

confidence: 99%

“…For purely scattering particles, changes in photolysis in this wavelength range are reduced by large cancellations in direct and diffuse light (Michelangeli et al, 1989). Light scattering by the El Chichón volcanic cloud was estimated to reduce O 2 photolysis by about 10 % (Michelangeli et al, 1989). The overall effect of scattering seems to be to reduce ozone formation (Pitari et al, 2014).…”

Section: Ultraviolet Scattering and Absorptionmentioning

confidence: 99%

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Radiative and chemical implications of the size and composition of aerosol particles in the existing or modified global stratosphere

et al. 2021

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Abstract. The size of aerosol particles has fundamental effects on their chemistry and radiative effects. We explore those effects using aerosol size and composition data in the lowermost stratosphere along with calculations of light scattering. In the size range between about 0.1 and 1.0 µm diameter (accumulation mode), there are at least two modes of particles in the lowermost stratosphere. The larger mode consists mostly of particles produced in the stratosphere, and the smaller mode consists mostly of particles transported from the troposphere. The stratospheric mode is similar in the Northern and Southern Hemisphere, whereas the tropospheric mode is much more abundant in the Northern Hemisphere. The purity of sulfuric acid particles in the stratospheric mode shows that there is limited production of secondary organic aerosol in the stratosphere, especially in the Southern Hemisphere. Out of eight sets of flights sampling the lowermost stratosphere (four seasons and two hemispheres) there were three with large injections of specific materials: volcanic, biomass burning, or dust. The stratospheric and tropospheric modes have very different roles for radiative effects on climate and for heterogeneous chemistry. Because the larger particles are more efficient at scattering light, most of the radiative effect in the lowermost stratosphere is due to stratospheric particles. In contrast, the tropospheric particles can have more surface area, at least in the Northern Hemisphere. The surface area of tropospheric particles could have significant implications for heterogeneous chemistry because these particles, which are partially neutralized and contain organics, do not correspond to the substances used for laboratory studies of stratospheric heterogeneous chemistry. We then extend the analysis of size-dependent properties to particles injected into the stratosphere, either intentionally or from volcanoes. There is no single size that will simultaneously maximize the climate impact relative to the injected mass, infrared heating, potential for heterogeneous chemistry, and undesired changes in direct sunlight. In addition, light absorption in the far ultraviolet is identified as an issue requiring more study for both the existing and potentially modified stratosphere.

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Section: Ultraviolet Scattering and Absorptionmentioning

confidence: 99%

Section: Ultraviolet Scattering and Absorptionmentioning

confidence: 99%

Radiative and chemical implications of the size and composition of aerosol particles in the existing or modified global stratosphere

et al. 2021

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“…An in depth analysis of the physicochemical aspects of SOAs formation in the upper troposphere and stratosphere is beyond the scope of this work. The reader is referred to published literature on the subject (Hallquist et al, 2009; Martinsson et al, 2019; Yee et al, 2013).…”

Section: Estimation Of Injected Stratospheric Aerosol Massmentioning

confidence: 99%

Stratospheric Injection of Massive Smoke Plume From Canadian Boreal Fires in 2017 as Seen by DSCOVR‐EPIC, CALIOP, and OMPS‐LP Observations

Torres

Bhartia

Taha³

et al. 2020

JGR Atmospheres

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“…The particle's organic mass fraction ranged from 30 wt% to 70 wt%, depending on the altitude and the air mass origin (Froyd et al, 2009). A recent study, spanning 10 years of filter measurements, showed a dominant contribution of sulfate or organics depending on location, altitude, and season (Martinsson et al, 2019). In a recent study, Höpfner et al (2019) detected and identified crystalline ammonium nitrate particles in the upper troposphere during the Asian monsoon period.…”

Section: Introductionmentioning

confidence: 98%

Ice nucleation ability of Ammonium Sulfate aerosol particles internally mixed with Secondary Organics

Bertozzi¹,

Wagner²,

Höhler³

et al. 2021

Preprint

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Abstract. The abundance of aerosol particles and their ability to catalyze ice nucleation are key parameters to correctly understand and describe the aerosol indirect effect on the climate. Cirrus clouds strongly influence the Earth's radiative budget, but their effect is highly sensitive to their formation mechanism, which is still poorly understood. Sulfate and organics are among the most abundant aerosol components in the troposphere and have also been found in cirrus ice crystal residuals. Most of the studies on ice nucleation at cirrus cloud conditions looked at either purely inorganic or purely organic particles. However, particles in the atmosphere are mostly found as internal mixtures, the ice nucleation ability of which is not yet fully characterized. In this study, we investigated the ice nucleation ability of internally mixed particles composed of crystalline ammonium sulfate (AS) and secondary organic material (SOM) at temperatures between −50 °C and −65 °C. The SOM was generated from the ozonolysis of α-pinene. The experiments were conducted in a large cloud chamber, which also allowed to simulate various aging processes that the particles may experience during their transport in the atmosphere, like cloud cycling and redistribution of the organic matter. We found that the ice nucleation ability of the mixed AS/SOM particles is strongly dependent on the particle morphology. If the organic matter is evenly distributed around the AS crystals in a core-shell morphology, small organic mass fractions of 5–8 wt% are sufficient to completely mask the heterogeneous ice nucleation ability of the inorganic core. In this case, the ice nucleation onset increased from a saturation ratio with respect to ice Sice ~ 1.30 for the pure AS crystals to ≥ 1.45 for the SOM-coated AS crystals. However, if such SOM-coated AS crystals are subjected to the mentioned aging processes, they show an improved ice nucleation ability with the ice nucleation onset at Sice ~ 1.35. We suggest that the aging processes change the particle morphology. The organic matter might redistribute on the surface to form a partially engulfed structure, where the ice-active sites of the AS crystals are no longer completely masked by the organic coating, or the morphology of the organic coating layer might transform from a compact to a porous structure. Our results underline the complexity to represent the ice nucleation ability of internally mixed particles in cloud models. They also demonstrate the need to further investigate the impact of atmospheric aging and cloud processing on the morphology and related ice nucleation ability of internally mixed particles.

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Formation and composition of the UTLS aerosol

Cited by 28 publications

References 67 publications

Radiative and chemical implications of the size and composition of aerosol particles in the existing or modified global stratosphere

Radiative and chemical implications of the size and composition of aerosol particles in the existing or modified global stratosphere

Stratospheric Injection of Massive Smoke Plume From Canadian Boreal Fires in 2017 as Seen by DSCOVR‐EPIC, CALIOP, and OMPS‐LP Observations

Ice nucleation ability of Ammonium Sulfate aerosol particles internally mixed with Secondary Organics

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