Spectral Shortwave Radiative Closure Studies at SGP: Improved Treatment of Aerosol Properties

Jennifer Delamere Tech-X Corporation
Joseph Michalsky Cooperative Institute for Research in Environmental Sciences
Peter Kiedron National Oceanic and Atmospheric Administration
Connor Flynn Pacific Northwest National Laboratory
Eli Mlawer Atmospheric & Environmental Research, Inc.
Annette Koontz Pacific Northwest National Laboratory
Sally McFarlane U.S. Department of Energy
Krista Gaustad Pacific Northwest National Laboratory

Category: Aerosol Properties

Working Group: Aerosol Life Cycle

Understanding regional aerosol processes and precisely representing them in climate models is an essential requirement for producing accurate simulations of future climate. Over the past decade, the Atmospheric Radiation Measurement (ARM) Program has put forth significant effort to characterize the radiative properties of atmospheric aerosols above the ARM Climate Research Facility sites. A ground-based Aerosol Observing System (AOS) continuously measures extensive aerosol properties from which intensive properties such as single-scattering albedo, asymmetry parameter, and Ångström exponent can be determined. These aerosol properties have been combined into value-added products (VAPs), such as the Aerosol Best Estimate, that are made available to the community. Ground-based radiometric measurements from the ARM Facility sites serve an equally important role in aerosol characterization. Not only is the aerosol optical depth derived from such measurements, but these measurements are used in radiative closure studies in which spectrally resolved measurements are compared with radiative transfer model calculations; the analysis of the measurement-model disagreement is targeted at resolving the source of the disagreement. This poster presents results from a continuing clear-sky radiative-closure study that utilizes Rotating Shadowband Spectroradiometer (RSS) measurements of the direct-normal, diffuse-horizontal, and total-horizontal irradiances from 360 to 1050 nm. The radiative transfer model for this study is the numerically accurate Code for High Resolution Accelerated Radiative Transfer with Scattering (CHARTS). A new aspect of this study is the utilization of recently updated aerosol products, which include a first evaluation of spectral hygroscopic growth factors and aerosol optical properties derived from the AOS measurements. Albedos from the Surface Spectral Albedo VAP will also be used for the first time in this shortwave radiative closure effort.

This poster will be displayed at ASR Science Team Meeting.

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