Particle size distributions in an expanding plume undergoing simultaneous coagulation and condensation

In previous work [Turco and Yu, 1997, 1998], analytical solutions of the eq uations describing aerosol coagulation in an expanding plume were derived. Those solutions were shown to depend on a single dimensionless time-depende nt number, N-T which is related to the particle coagulation kernel and the plume volume. Here these results are extended to the case in which a vapor, either primary or secondary, is also condensing on the aerosol. We show th at for several important regimes of condensation encountered in the atmosph ere, relatively simple empirical relations can be deduced that accurately d escribe the evolving particle size distribution, again in terms of N-T In a ddition, the effects on the plume aerosol of entrained background particles and gases are explicitly treated. These new analytical solutions offer ins ights into the physics governing the evolution of aerosol plumes under atmo spheric conditions, lead to a simple methodology for carrying out sensitivi ty studies, allow objective testing and validation of numerical codes and p rovide a useful means of extrapolating from plume scales to the scales appr opriate for regional. and global modeling.