Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 5.668 IF 5.668
  • IF 5-year value: 6.201 IF 5-year
    6.201
  • CiteScore value: 6.13 CiteScore
    6.13
  • SNIP value: 1.633 SNIP 1.633
  • IPP value: 5.91 IPP 5.91
  • SJR value: 2.938 SJR 2.938
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 174 Scimago H
    index 174
  • h5-index value: 87 h5-index 87
Volume 12, issue 5
Atmos. Chem. Phys., 12, 2345-2355, 2012
https://doi.org/10.5194/acp-12-2345-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Atmos. Chem. Phys., 12, 2345-2355, 2012
https://doi.org/10.5194/acp-12-2345-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 02 Mar 2012

Research article | 02 Mar 2012

Atmospheric Cluster Dynamics Code: a flexible method for solution of the birth-death equations

M. J. McGrath1,2, T. Olenius1, I. K. Ortega1, V. Loukonen1, P. Paasonen1, T. Kurtén1, M. Kulmala1, and H. Vehkamäki1 M. J. McGrath et al.
  • 1Department of Physics, P.O. Box 64, University of Helsinki, 00014, Helsinki, Finland
  • 2Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan

Abstract. 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.

Publications Copernicus
Download
Citation
Share