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| Titel |
Interactions of meteoric smoke particles with sulphuric acid in the Earth's stratosphere |
| VerfasserIn |
R. W. Saunders, S. Dhomse, W. S. Tian, M. P. Chipperfield, J. M. C. Plane |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 12, no. 10 ; Nr. 12, no. 10 (2012-05-16), S.4387-4398 |
| Datensatznummer |
250011157
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| Publikation (Nr.) |
 copernicus.org/acp-12-4387-2012.pdf |
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| Zusammenfassung |
Nano-sized meteoric smoke particles (MSPs) with iron-magnesium silicate
compositions, formed in the upper mesosphere as a result of meteoric
ablation, may remove sulphuric acid from the gas-phase above 40 km and may
also affect the composition and behaviour of supercooled
H2SO4-H2O droplets in the global stratospheric aerosol (Junge)
layer.
This study describes a time-resolved spectroscopic analysis of the evolution
of the ferric (Fe3+) ion originating from amorphous ferrous
(Fe2+)-based silicate powders dissolved in varying Wt % sulphuric
acid (30–75 %) solutions over a temperature range of 223–295 K. Complete
dissolution of the particles was observed under all conditions. The
first-order rate coefficient for dissolution decreases at higher Wt % and
lower temperature, which is consistent with the increased solution viscosity
limiting diffusion of H2SO4 to the particle surfaces. Dissolution
under stratospheric conditions should take less than a week, and is much
faster than the dissolution of crystalline Fe2+ compounds.
The chemistry climate model UMSLIMCAT (based on the UKMO Unified
Model) was then used to study the transport of MSPs through the middle
atmosphere. A series of model experiments were performed with different
uptake coefficients. Setting the concentration of 1.5 nm radius MSPs at
80 km to 3000 cm−3 (based on rocket-borne charged particle
measurements), the model matches the reported Wt % Fe values of 0.5–1.0 in
Junge layer sulphate particles, and the MSP optical extinction between 40 and
75 km measured by a satellite-borne spectrometer, if the global meteoric
input rate is about 20 tonnes per day. The model indicates that an uptake
coefficient ≥0.01 is required to account for the observed two orders of
magnitude depletion of H2SO4 vapour above 40 km. |
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