Characterization and evolution of tropospheric plumes from Lascar and Villarrica volcanoes, Chile
116
Citation
77
Reference
10
Related Paper
Citation Trend
Abstract:
Direct sampling (filter pack and impactor) and remote sensing (ultraviolet spectroscopy and Sun photometry) of the plumes of Lascar and Villarrica volcanoes, Chile, reveal that both are significant and sustained emitters of SO 2 (28 and 3.7 kg s −1 , respectively), HCl (9.6 and 1.3 kg s −1 , respectively), HF (4.5 and 0.3 kg s −1 , respectively) and near‐source sulfate aerosol (0.5 and 0.1 kg s −1 , respectively). Aerosol plumes are characterized by particle number fluxes (0.08–4.0 μm radius) of ∼10 17 s −1 (Lascar) and ∼10 16 s −1 (Villarrica), the majority of which will act as cloud condensation nuclei at supersaturations >0.1%. Impactor studies suggest that the majority of these particles contain soluble SO 4 2− . Most aerosol size distributions were bimodal with maxima at radii of 0.1–0.2 μm and 0.7–1.5 μm. The mean particle effective radius ( R eff ) ranged from 0.1 to 1.5 μm, and particle size evolution during transport appears to be controlled by particle water uptake (Villarrica) or loss (Lascar) rather than sulfate production.Keywords:
Cloud condensation nuclei
Particle (ecology)
Biogenic sources contribute to cloud condensation nuclei (CCN) in the clean marine atmosphere, but few measurements exist to constrain climate model simulations of their importance. The chemical composition of individual atmospheric aerosol particles showed two types of sulfate-containing particles in clean marine air masses in addition to mass-based Estimated Salt particles. Both types of sulfate particles lack combustion tracers and correlate, for some conditions, to atmospheric or seawater dimethyl sulfide (DMS) concentrations, which means their source was largely biogenic. The first type is identified as New Sulfate because their large sulfate mass fraction (63% sulfate) and association with entrainment conditions means they could have formed by nucleation in the free troposphere. The second type is Added Sulfate particles (38% sulfate), because they are preexisting particles onto which additional sulfate condensed. New Sulfate particles accounted for 31% (7 cm-3) and 33% (36 cm-3) CCN at 0.1% supersaturation in late-autumn and late-spring, respectively, whereas sea spray provided 55% (13 cm-3) in late-autumn but only 4% (4 cm-3) in late-spring. Our results show a clear seasonal difference in the marine CCN budget, which illustrates how important phytoplankton-produced DMS emissions are for CCN in the North Atlantic.
Cloud condensation nuclei
Dimethyl sulfide
Supersaturation
Sulfate aerosol
Cite
Citations (205)
Measurements in the plume from an isolated copper and lead smelting operation in northeastern Australia have been made from an aircraft to a distance of 560 km from the source. The aim was to gain information on the composition, numbers and sizes of cloud condensation nuclei (CCN) emitted by this very strong source, with a view to later relating this information to the differences in properties between clouds affected and unaffected by the plume. In the cloudless, inversion-limited conditions of the winter months the particulate plume retained a coherent, easily detected shape out to the largest distance worked, 560 km downwind of the source at which point the plume was 260 km wide. The Aitken particle flux ranged from ∼2 × 1018 s−1, measured between 56 and 185 km downwind, to >1019 s−1 at distances >370 km downwind. The increase in flux and changes in the size distribution of particles collected from the plume as a function of distance downwind suggest that gas-phase oxidation of sulphur dioxide in the plume leads to nucleation of new particles as the plume disperses. Knowledge of the size distribution and chemical composition of the particles enabled CCN concentrations to be calculated. In this way the flux of CCN active at 0.5% supersaturation (S) was estimated to range from a minimum of ∼5 × 1017 s−1 at 90 km downwind to ∼5 × 1018 s−1 at 500 km downwind. This latter figure is thought to equal ∼0.1% of the global, natural production rate of particles active at 0.5% S.
Cloud condensation nuclei
Supersaturation
Panache
Ice nucleus
Point source
Particle (ecology)
Cite
Citations (15)