SIMPCCGAS · Simulating and Simplifying the Physicochemical Complexity of Gas-Aerosol Systems to Promote Development of the Next Generation of Atmospheric 3-D Models

Observed levels of organic aerosol, of which the major fraction is secondary organic aerosol (SOA) formed from the oxidation of gaseous precursors and gas-particle partitioning, show that organics typically contribute 30% to 80% of the aerosol mass in the troposphere. It is of central importance for actions targeting the improvement of urban and regional air quality as well as the critical assessment of climate sensitivity, to understand how chemistry and partitioning of condensable organic and inorganic species influences mass concentrations, chemical composition, and size distribution of atmospheric aerosols. Current atmospheric 3-D models implement physicochemical processes by means of highly simplified schemes only. Most of these models substantially underpredict observed aerosol levels, constituting one of the main uncertainties in current assessments of air quality and climate change.In this project, we propose to develop a novel physicochemical modeling framework enabling simulations of aerosol formation and chemical evolution, and the evaluation and design of complex smog chamber experiments. The fundamental insights gained from a detailed model comprising the main physicochemical processes of aerosol formation and chemical aging provides a sound basis from which to assess the feasibility of different levels of simplifications, such as the number and classes of organic surrogate compounds required for process parameterizations in 3-D models. This will allow the formulation of constraints and new parameterizations promoting the development of next-generation atmospheric models. The project brings together a talented fellow, skilled in modeling and thermodynamics, with a highly experienced team at the host institute, the Laboratory of Atmospheric Chemistry at PSI. A network of scientific collaborations with groups in Europe and the USA will foster mutually beneficial knowledge transfer and spur the project developments towards its highly valuable goals.""