In this study we apply the particle-based scheme of Shima et al. 2009. Modeled particles (aka super-droplets) are a numerical proxy for a multiplicity of real-world CCN, cloud, drizzle or rain particles of the same size, nucleus type, and position. Tracking cloud nucleus properties is an inherent feature of the particle-based frameworks, making them suitable for studying aerosol-cloud-aerosol interactions. Moreover, the super-droplet approach is characterized by linear scalability in the number of computational particles, and no numerical diffusion in its condensational and collisional (Monte-Carlo) growth schemes.
We will present simulations using a kinematic model of a stratocumulus cloud. The simulations are carried out using a setup inspired by the VOCALS campaign (Grabowski& Lebo, see http://www.rap.ucar.edu/~gthompsn/workshop2012/case1/). The initial conditions are defined by the dry aerosol size spectrum and the vertical profiles of the temperature and humidity. The prescribed flow mimics a single eddy spanning from the sea surface up to the inversion. Thus, within the simulated domain both updraft and downdraft regions are present. Employment of a kinematic framework allows (and limits) to focus solely on the microphysical aspects of aerosol-cloud-aerosol interactions, excluding any coupling with cloud dynamics, and simplifying the underlying numerics.
The super-droplet approach features particle-level formulation of condensational growth (including CCN activation and evaporation), and collisional growth. This presentation will be focused on representation of aqueous-phase chemistry within the super-droplet framework. This extension is being implemented with the aim to cover processes leading e.g. to presence of the so-called "Hoppel gap" in the size spectrum of the cloud-processed aerosol.