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| Titel |
A pathway analysis of global aerosol processes |
| VerfasserIn |
N. A. J. Schutgens, P. Stier |
| 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 ; 14, no. 21 ; Nr. 14, no. 21 (2014-11-06), S.11657-11686 |
| Datensatznummer |
250119141
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| Publikation (Nr.) |
 copernicus.org/acp-14-11657-2014.pdf |
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| Zusammenfassung |
| We present a detailed budget of the changes in atmospheric aerosol mass and
numbers due to various processes: emission (including instant condensation of
soluble biogenic emissions), nucleation, coagulation, H2SO4
condensation and in-cloud production, aging and deposition. The budget is
created from monthly averaged tracer tendencies calculated by the global
aerosol model ECHAM5.5-HAM2 and allows us to investigate process
contributions at various length-scales and timescales. As a result, we show in
unprecedented detail what processes drive the evolution of aerosol. In
particular, we show that the processes that affect aerosol masses are quite
different from those that affect aerosol numbers. Condensation of H2SO4
gas onto pre-existing particles is an important process, dominating the
growth of small particles in the nucleation mode to the Aitken mode and the
aging of hydrophobic matter. Together with in-cloud production of
H2SO4, it significantly contributes to (and often dominates) the mass
burden (and hence composition) of the hydrophilic Aitken and accumulation
mode particles. Particle growth itself is the leading source of number
densities in the hydrophilic Aitken and accumulation modes, with their
hydrophobic counterparts contributing (even locally) relatively little. As
expected, the coarse mode is dominated by primary emissions and mostly
decoupled from the smaller modes. Our analysis also suggests that coagulation
serves mainly as a loss process for number densities and that, relative to
other processes, it is a rather unimportant contributor to composition
changes of aerosol. The analysis is extended with sensitivity studies where
the impact of a lower model resolution or pre-industrial emissions is shown
to be small. We discuss the use of the current budget for model
simplification, prioritization of model improvements, identification of
potential structural model errors and model evaluation against observations. |
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