Environmental & Climate Sciences Department Seminar

Aerosol-cloud interaction and cloud processes are reasons for some of the large uncertainties in future climate projections. A multifaceted approach of theory, observation, and idealized simulation is essential to understanding and representing a cloud process in climate models. Measurements of steady-state clouds produced in the Pi convection cloud chamber at the Michigan Technological University have helped us understand the role of turbulence in droplet activation and cloud microphysical properties. Idealized numerical modeling studies complement laboratory observations by providing high spatial and temporal resolution results. Despite advances in computing, Direct Numerical Simulation (DNS) of the convection and cloud microphysics in the Pi chamber is barely feasible. Therefore, we are using the computationally economical One-Dimensional Turbulence (ODT) model that resolves all relevant scales in one dimension as well as individual droplets to study the effects of aerosol and turbulence on droplet size distribution in the chamber. The ODT is a stochastic model that has been successfully used to simulate dry and moist (no cloud) Rayleigh-Bernard convection (RBC). We modified the ODT model to include particle-by-particle Lagrangian microphysics. We compare the cloudy ODT model results against Pi chamber observations to evaluate the ODT model's ability to simulate the observed droplet size distribution for various aerosol injection rates that correspond to different supersaturation regimes (mean-dominated, fluctuation-influenced, and fluctuation-dominated). The ODT model has the potential to simulate a much larger cloud chamber at a high resolution to understand the drizzle formation process, which is a critical knowledge gap in the warm rain formation.