Simulating of aerosol nucleation bursts

Version 20110324

Hannes.Tammet@ut.ee

The program Burstsimulator.exe is an implementation of the numerical model for atmospheric aerosol nucleation bursts described in the papers by Tammet and Kulmala (2005, 2007). The program and accompanying files are incorporated into the package Burstsimulator.zip. The program includes a minimum of physical assumptions and 99 user-controlled parameters. The model is based on computationally efficient parameterization of submodels, which allow considering

• the neutral and ion-induced nucleation,
• depletion of nanoparticles and ions on the pre-existing aerosol,
• depletion of nanoparticles and ions on the needles of conifer forest,
• the electric charges of particles,
• the molecular dipole moments and the polarization interaction,
• the nano-Köhler growth function,
• the molecule-particle interception,
• quantum retardation of sticking.

The model includes an improved submodel of the sink of ions and nucleation mode particles on large particles. The deposition on the needles of conifer forest is estimated using the Churchill-Bernstein approximation, which is adapted from the theory of heat transfer. The evolution of the size distribution is computed using a sectional model with several thousands of sections. Computing time on an ordinary PC is counted in seconds in case of a typical task with several thousands of time steps and several thousands of size sections.

 

The present simulator is an updated version of the old program dated 20060912. Main changes are:

• function Mobility is corrected for multiply charged particles, however, without any effect in the functionality and the results of the present program,
• the output of mobility distributions, which was declared in the manual of the old version but not properly realized in the old program, is implemented in the new version,
• two new types of output tables is available: diagram tables support convenient drawing of distribution diagrams corresponding to the end of the evolution period and plot tables help to draw the contour plots using the MatLab function Burstplot.m, which is included into the package Burstsimulator.zip,
• the output files can be ordered in any combination using the modified control line 61,
• additional control lines are included into the control file where the last four lines are:
  95) geometric standard deviation of the size distribution of positive small ions,
  96) geometric standard deviation of the size distribution of negative small ions,
  97) version of the plot table composition,
  98) the symbol of indeterminacy.

The nucleation process is calculated assuming the monodisperse small ions and the standard deviations above are considered only when compiling the plot tables, where the small ions are spread around the average mobility according to the lognormal law taking into account the control lines 95 and 96.

More information about the Burstsimulator is available in the manual.

 

References

Tammet, H. & Kulmala, M. (2005) Simulation tool for atmospheric aerosol nucleation bursts. J. Aerosol Sci. 36, 173–196, http://dx.doi.org/doi:10.1016/j.jaerosci.2004.08.004.

Tammet, H. & Kulmala, M. (2007) Simulating aerosol nucleation bursts in a coniferous forest, Boreal Env. Res. 12, 421–430, http://www.borenv.net/BER/pdfs/ber12/ber12-421.pdf.