Variable CCN formation potential of regional sulfur emissions

Manktelow, P. T.; Carslaw, K. S.; Mann, G. W.; Spracklen, Dominick V.

doi:10.5194/acp-9-3253-2009

Cited by 18 publications

(9 citation statements)

References 38 publications

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“…CCN concentrations at the altitude of low-level clouds are predicted to increase by a factor ∼14 in Asia. Such a long-range effect is consistent with our previous studies of regional air pollution transport (Manktelow et al, 2009). Volcanic SO 2 is lofted into the free troposphere where the formed H 2 SO 4 vapour causes rapid nucleation of new particles at low temperatures.…”

Section: Discussionsupporting

confidence: 79%

“…We show in Sect. 3.5.2 that even small amounts of SO 4 can have a substantial effect on CCN, consistent with our previous study (Manktelow et al, 2009). Figure 3 shows the global monthly mean atmospheric SO 2 and SO 4 burdens (i.e.…”

Section: Experimental Design and Emissionssupporting

confidence: 75%

“…an enhancement in CN concentration by a factor ∼2 to ∼5 in those regions). This far-reaching impact on CN concentrations is due to the long-range transport of nucleated particles as previously reported by Manktelow et al (2009).…”

Section: Aerosol Microphysical Processes and Size Distributionmentioning

confidence: 57%

“…Although the mass of sulphate is quite small far from the eruption, it is present in a large number of small particles that are very effective CCN. In Manktelow et al (2009) we showed that Asian pollutant sulphur emissions are lofted higher into the free troposphere than other regional emissions and therefore have a high "CCN formation potential". A similar high CCN formation potential applies to an eruption like Laki.…”

Section: Discussionmentioning

confidence: 95%

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The impact of the 1783–1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei

et al. 2010

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Abstract. The 1783-1784 AD Laki flood lava eruption commenced on 8 June 1783 and released 122 Tg of sulphur dioxide gas over the course of 8 months into the upper troposphere and lower stratosphere above Iceland. Previous studies have examined the impact of the Laki eruption on sulphate aerosol and climate using general circulation models. Here, we study the impact on aerosol microphysical processes, including the nucleation of new particles and their growth to cloud condensation nuclei (CCN) using a comprehensive Global Model of Aerosol Processes (GLOMAP). Total particle concentrations in the free troposphere increase by a factor ∼16 over large parts of the Northern Hemisphere in the 3 months following the onset of the eruption. Particle concentrations in the boundary layer increase by a factor 2 to 5 in regions as far away as North America, the Middle East and Asia due to long-range transport of nucleated particles. CCN concentrations (at 0.22% supersaturation) increase by a factor 65 in the upper troposphere with maximum changes in 3-month zonal mean concentrations of ∼1400 cm −3 at high northern latitudes. 3-month zonal mean CCN concentrations in the boundary layer at the latitude of the eruption increase by up to a factor 26, and averaged over the Northern Hemisphere, the eruption caused a factor 4 increase in CCN concentrations at low-level cloud altitude. The simulations show that the Laki eruption would have completely dominated as a source of CCN in the pre-industrial atmosphere. The model also suggests an impact of the eruption in the Southern Hemisphere, where CCN concentrations are increased by up to a factor 1.4 at 20 • S. Our model simulations suggest that the impact of an equivalent wintertime eruption on upper tropoCorrespondence to: A. Schmidt (a.schmidt@see.leeds.ac.uk) spheric CCN concentrations is only about one-third of that of a summertime eruption. The simulations show that the microphysical processes leading to the growth of particles to CCN sizes are fundamentally different after an eruption when compared to the unperturbed atmosphere, underlining the importance of using a fully coupled microphysics model when studying long-lasting, high-latitude eruptions.

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Section: Discussionsupporting

confidence: 79%

Section: Experimental Design and Emissionssupporting

confidence: 75%

Section: Aerosol Microphysical Processes and Size Distributionmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 95%

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The impact of the 1783–1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei

et al. 2010

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“…from anthropogenic sources. For example, variations in the oxidation pathways of SO 2 also influence differences in the production of CCN from anthropogenic SO 2 from different continents (Manktelow et al, 2009). The results are particularly important for CCN production from shipping emissions.…”

Section: Discussionmentioning

confidence: 94%

Sensitivity of cloud condensation nuclei to regional changes in dimethyl-sulphide emissions

et al. 2013

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The atmospheric oxidation of dimethyl-sulphide (DMS) derived from marine phytoplankton is a significant source of marine sulphate aerosol. DMS has been proposed to regulate climate via changes in cloud properties, though recent studies have shown that present-day global cloud condensation nuclei (CCN) concentrations have only a weak dependence on the total emission flux of DMS. Here, we use a global aerosol microphysics model to examine how efficiently CCN are produced when DMS emissions are changed in different marine regions. We find that global CCN production per unit mass of sulphur emitted varies by more than a factor of 20 depending on where the change in oceanic DMS emission flux is applied. The variation in CCN production efficiency depends upon where CCN production processes (DMS oxidation, SO₂ oxidation, nucleation and growth) are most efficient and removal processes (deposition) least efficient. The analysis shows that the production of aerosol sulphate through aqueous-phase oxidation of SO₂ limits the amount of H₂SO₄ available for nucleation and condensational growth and therefore suppresses CCN formation, leading to the weak response of CCN to changes in DMS emission. Our results show that past and future changes in the spatial distribution of DMS emissions (through changes in the phytoplankton population or wind speed patterns) could exert a stronger control on climate than net increases in biological productivity

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Causes and importance of new particle formation in the present‐day and preindustrial atmospheres

et al. 2017

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New particle formation has been estimated to produce around half of cloud‐forming particles in the present‐day atmosphere, via gas‐to‐particle conversion. Here we assess the importance of new particle formation (NPF) for both the present‐day and the preindustrial atmospheres. We use a global aerosol model with parametrizations of NPF from previously published CLOUD chamber experiments involving sulfuric acid, ammonia, organic molecules, and ions. We find that NPF produces around 67% of cloud condensation nuclei at 0.2% supersaturation (CCN0.2%) at the level of low clouds in the preindustrial atmosphere (estimated uncertainty range 45–84%) and 54% in the present day (estimated uncertainty range 38–66%). Concerning causes, we find that the importance of biogenic volatile organic compounds (BVOCs) in NPF and CCN formation is greater than previously thought. Removing BVOCs and hence all secondary organic aerosol from our model reduces low‐cloud‐level CCN concentrations at 0.2% supersaturation by 26% in the present‐day atmosphere and 41% in the preindustrial. Around three quarters of this reduction is due to the tiny fraction of the oxidation products of BVOCs that have sufficiently low volatility to be involved in NPF and early growth. Furthermore, we estimate that 40% of preindustrial CCN0.2% are formed via ion‐induced NPF, compared with 27% in the present day, although we caution that the ion‐induced fraction of NPF involving BVOCs is poorly measured at present. Our model suggests that the effect of changes in cosmic ray intensity on CCN is small and unlikely to be comparable to the effect of large variations in natural primary aerosol emissions.

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Variable CCN formation potential of regional sulfur emissions

Cited by 18 publications

References 38 publications

The impact of the 1783–1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei

The impact of the 1783–1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei

Sensitivity of cloud condensation nuclei to regional changes in dimethyl-sulphide emissions

Causes and importance of new particle formation in the present‐day and preindustrial atmospheres

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