2018 Fall Meeting

10-15 December

Despite decades of study, aerosol-cloud interactions remain the largest uncertainty in climate projections, partly due to the chemical and physical complexity of aerosols in the atmosphere, and how we describe, measure and model it. Atmospheric aerosols are complex mixtures of different chemical species, and individual particles exist in many different shapes and morphologies. Together these characteristics are called the aerosol mixing state. This tutorial begins with an overview of the main aerosol types and their relevance in the atmospheric system. We will synthesize our knowledge of aerosol mixing state’s fundamental impact on climate-relevant properties, such as cloud condensation, ice nuclei concentration and aerosol optical properties. Findings are presented within a framework that defines aerosol mixing state along with appropriate mixing state metrics to quantify it. We then give an overview of measurement techniques to probe aerosol mixing state and discuss how aerosol mixing state is represented in atmospheric models at different scales. Future research directions are identified, with a focus on the need for integrating mixing state measurements and modeling. Taken together, this tutorial communicates how aerosol mixing state relates to climate-relevant aerosol properties and why improved understanding of these topics is needed to reduce uncertainties related to aerosol-cloud interactions.

• A - Atmospheric Sciences