Ten years of aerosol chemical and optical properties at SGP and NSA: building regional aerosol models for radiative transfer

Description

Primary grounds for uncertainty in constraining aerosol radiative forcing are (1) the ability to characterize the spatial and temporal distribution of different aerosol types across the globe and (2) understanding the relationship between aerosol chemical, physical, and optical properties. Long-term observations of global aerosol from space show that, while aerosol is highly variable through space and time, seasonal and regional average aerosol amounts are remarkably consistent. However, space-based measurements are not well suited to determining aerosol type or intensive optical properties required for calculating radiative forcing. Climate models determine aerosol optical properties from estimated distributions of chemical and physical properties, hence, characterizing the relationship between these and optical properties is critical for model evaluation. Well-distributed, continuous, ground-based monitoring at regionally representative sites can provide constraints on the global distribution of relevant aerosol properties. We use decade-long data sets from the Southern Great Plains (SGP) and North Slope of Alaska (NSA) sites to characterize the temporal variability of aerosol optical properties and radiative forcing and to examine the relationship of this variability to their chemical composition. The results are used to evaluate standard aerosol models that are required to convert aerosol mass and number by chemical species to optical properties for assessing the radiative impact of aerosol on current and future climate.