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| Titel |
Atmospheric Cluster Dynamics Code: a flexible method for solution of the birth-death equations |
| VerfasserIn |
M. J. McGrath, T. Olenius, I. K. Ortega, V. Loukonen, P. Paasonen, T. Kurtén, M. Kulmala  , H. Vehkamäki |
| 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. 5 ; Nr. 12, no. 5 (2012-03-02), S.2345-2355 |
| Datensatznummer |
250010848
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| Publikation (Nr.) |
 copernicus.org/acp-12-2345-2012.pdf |
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| Zusammenfassung |
| The Atmospheric Cluster Dynamics Code (ACDC) is presented and
explored. This program was created to study the first steps of
atmospheric new particle formation by examining the formation of
molecular clusters from atmospherically relevant molecules. The
program models the cluster kinetics by explicit solution of the
birth–death equations, using an efficient computer script for their
generation and the MATLAB ode15s routine for their solution.
Through the use of evaporation rate coefficients derived from
formation free energies calculated by quantum chemical methods for
clusters containing dimethylamine or ammonia and sulphuric acid, we
have explored the effect of changing various parameters at
atmospherically relevant monomer concentrations. We have included in
our model clusters with 0–4 base molecules and 0–4 sulfuric acid
molecules for which we have commensurable quantum chemical data. The
tests demonstrate that large effects can be seen for even small
changes in different parameters, due to the non-linearity of the
system. In particular, changing the temperature had a significant
impact on the steady-state concentrations of all clusters, while the
boundary effects (allowing clusters to grow to sizes beyond the
largest cluster that the code keeps track of, or forbidding such
processes), coagulation sink terms, non-monomer collisions, sticking
probabilities and monomer concentrations did not show as large
effects under the conditions studied. Removal of coagulation sink
terms prevented the system from reaching the steady state when all the
initial cluster concentrations were set to the default value of
1 m−3, which is probably an effect caused by studying only
relatively small cluster sizes. |
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