Research project

Research project objectives

The project aims at developing a numerical model for studying aerosol processing by clouds. It responds to the pressing need for the development of effective tools for research of aerosol processing by clouds, for which even the most sophisticated traditional cloud microphysics approaches are either inadequate or impractical.

Aerosols and clouds have been identified to contribute significantly to the Earth's radiation budget and therefore play an important, yet still poorly understood, role in the radiation imbalance of projected climate variations (IPCC, 2007). Clouds process atmospheric aerosol by taking part in its wet deposition and cloud condensation nuclei regeneration through evaporation of cloud droplets and drizzle. Understanding the way clouds process aerosol is needed to comprehensively describe the interactions between aerosol, clouds, precipitation and radiation. The complexity of these interactions makes numerical simulation the only viable tool for investigating how natural and anthropogenic air pollution impacts the environment.

Research methodology

A Large Eddy Simulation (LES) framework capable of representing comprehensively processes leading to aerosol processing by clouds will be constructed by extending the existing cloud-simulation software package (icicle) being developed at the Institute of Geophysics, Faculty of Physics at the University of Warsaw (IGFUW). Up to now, the icicle framework allows performing only two- dimensional kinematic simulations with a prescribed flow field using a novel particle-based aerosol-cloud microphysics. The newly-developed icicle modules will constitute new implementations of the key components of the NCAR LES-type anelastic cloud model EULAG. The pioneering nature of the project is embodied in the coupling of an efficient description of cloud dynamics (EULAG’s MPDATA- based anelastic framework) with a novel treatment of aerosol-cloud-precipitation microphysics (the Super-Droplet method) within a robust numerical modelling tool. Neither MPDATA-based anelastic solvers nor particle-based microphysics modules are commonly available in presently developed models for cloud research, partially owing to the complexity of these algorithms.

It is planned also to extend the icicle implementation of the Super-Droplet scheme with representation of in-droplet aqueous chemical reactions.
The proposed development will be carried out in compliance with free and open-source software engineering practices employing modern coding techniques.

Research project impact

Coupling detailed particle-based microphysics with a state-of-the-art fluid dynamics solver within an open-source tool engineered using modern programming techniques will bring to the community a novel and effective tool for studying aerosol-cloud interactions. The openness and clarity of the source code, together with the completeness of the documentation will make the code auditable, and reusable by the community making the developed software a tool for genuinely reproducible research.

The proposed development aims at advancing both research and education. It will generate novel and important results readily publishable in peer-reviewed high-impact journals, and provide documented computer programs suitable for future Masters's and PhD projects.

International collaboration

The new icicle modules will be developed in collaboration with Drs Piotr Smolarkiewicz and Wojciech Grabowski from the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, USA. NCAR partners are internationally recognized experts in applications of computational fluid dynamics, with a wide-ranging portfolio of applications to all scale atmospheric problems. They both have a record of close collaboration with the Institute of Geophysics (IGFUW), Faculty of Physics, and University of Warsaw (their joint Alma Mater).

The current proposal is a consequent step in realizing a synergistic program, mutually beneficial to NCAR and IGFUW and begins a new chapter in the NCAR-IGFUW collaboration by starting a first-join software-development endeavour.