Toward Improved Understanding of Fundamental Processes Controlling the Size-Resolved Properties of Particles in the Stratosphere

In this research project, the PI will study the physical and chemical processes that control stratospheric aerosols which will advance our ability to characterize and understand phenomena associated with volcanic emissions and their resultant climate and chemistry impacts. There is a clear need to better understand stratospheric aerosol processes and this work will address existing data gaps related to new particle formation in the stratosphere. Specifically, the three data gaps to be addressed in this work are: (1) What are the key parameters that control new particle formation in the stratosphere and how extendible are the existing tropospheric models to stratospheric conditions? (2) What are the underlying microphysical and transport processes that lead to the observed aerosol properties that are not captured by existing models? (3) What are possible explanations for the shorter-than-observed model simulated stratospheric aerosol lifetime after major volcanic eruptions? These data gaps will be addressed via the following tasks. First, new mechanisms of particle nucleation in the stratosphere will be developed. Second, the processes which lead to the observed bimodal structure in accumulation mode particles in the stratosphere that are currently not captured in models will be studied. Third, potential reasons for faster-than-observed reductions in post-volcanic sulfate mass burdens in current models will be examined. The results and new parameterizations will be implemented via an Advanced Particle Microphysics model within the widely used GEOS-Chem model. This project will support and train a postdoctoral researcher, a graduate, and an undergraduate student, plus provide research experience for underrepresented high school senior students. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.