Inferring aerosol properties from space-based measurements: An alternative to direct retrieval

Abstract:

Stratospheric aerosol is a uniquely variable component of climate forcing that can increase almost instantaneously by multiple orders of magnitude following major volcanic eruptions. These events can have a significant impact on climate and can be evaluated as a surrogate for the use of human-derived stratospheric aerosol as mitigation for global warming. At this time, proscribed stratospheric aerosol data sets remain key inputs for climate models and also act as corroboration for models which produce their aerosol interactively. Space-based data sets have an extensive spatial extent and long (though inhomogeneous) temporal span that make them of particular utility to model applications. At the same time, they are exclusively measurements of aerosol optical properties (e.g., extinction coefficient) at a few wavelengths and their usage in models often requires transforming these measurements into inferences of aerosol size distribution from which model-required properties can be derived. It is well known that there are substantial limitations to the reliability of aerosol properties inferred from even the most robust data sets of aerosol optical properties. These limitations lead to significant uncertainties in important aerosol properties that are difficult to rectify. In this presentation, strategies to mitigate these issues are addressed particularly an approach that uses knowledge gained from the University of Wyoming optical particle counter (OPC) regarding the relationship between aerosol extinction coefficient and aerosol size distribution and applied to the long Stratospheric Aerosol and Gas Experiment (SAGE II) climatology.