Quadrature-Based Model for Simulating Cloud-Aerosol Interactions

Aerosol effects on shallow clouds are sensitive to particle physical and chemical properties, but these particle characteristics are not easily represented in large-scale simulations. Sparse representations of aerosol populations that accurately capture aerosol-cloud interactions are needed for regional- and global-scale chemical transport models. Here we introduce a new framework for simulating atmospheric aerosols based on the Quadrature Method of Moments. This new aerosol model has been designed to reproduce key features of benchmark populations simulated by the particle-resolved model PartMC-MOSAIC, while tracking as little information about aerosol distributions as is necessary. By applying principles of maximum entropy, the quadrature-based model efficiently reproduces CCN activity of the complex aerosol populations simulated by the particle-resolved model with high accuracy. Unlike the commonly used sparse representations, such as modal and sectional schemes, the maximum-entropy moment-based approach is not constrained to pre-determined size bins or assumed distribution shapes. This study is a first step toward a new aerosol simulation scheme that will track multivariate aerosol distributions with sufficient computational efficiency for large-scale simulations.