American Association for Aerosol Research - Abstract Submission

AAAR 39th Annual Conference
October 18 - October 22, 2021

Virtual Conference

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Estimation of Aerosol Direct Radiative Effect through CATCH-derived Aerosol Types

BETHANY SUTHERLAND, Nicholas Meskhidze, NC State University

     Abstract Number: 187
     Working Group: Aerosols, Clouds and Climate

Abstract
The ability to remotely assign aerosol types (i.e. Dust, Urban, Smoke, Fresh Smoke, and Maritime) from the High Spectral Resolution Lidar (HSRL) retrievals presents a promising opportunity for narrowing the uncertainty in global calculations of the Direct Radiative Effect (DRE) of aerosols. Here we present the results of using type-specific values of single scattering albedo (SSA) and asymmetry parameter (g) in DRE calculations over North America. Since spatiotemporal distributions of aerosol types are not currently available, aerosol types analogous to HSRL are determined using the CATCH (Creating Aerosol Types from Chemistry) algorithm (Dawson et al., 2017). Type-specific values are chosen using the GEOS-Chem chemical transport model. The CATCH-derived type specific values of SSA and g are compared with AERONET retrievals for locations and times where a single type contributed the majority of the extinction. DRE uncertainty calculations is estimated based on the spread in GEOS-Chem-derived SSA and g values due to intra-type variability in aerosol chemical composition. This spread in SSA and g is then compared to the range of values derived using aerosol microphysics from AEROCOM III models. Preliminary results from July of 2014 show that the CATCH/GEOS-Chem derived type-specific SSA and g are comparable with AERONET retrievals. Additionally intra-type variability of SSA and g, having mean inter-quartile ranges less than 0.01 and 0.032 respectively (due to variability in the chemical composition for aerosols of a single type), is generally lower than the spread in values derived from the AEROCOM models. This study indicates that using type-specific aerosol optical properties in conjunction with HSRL retrieved aerosol types could lead to DRE estimates with lower uncertainty than is currently achieved. Results spanning the entire year of 2014 will be presented, as well as an analysis of seasonal trends in type-specific optical properties.

References
Dawson, et al., https://doi.org/10.1002/2017JD026913