Optical Characterization of Polluted Atmospheric Aerosols Generated in a Tabletop Chamber

CHRISTIAN PATTYN, Jake Zenker, Lekha Patel, Andres Sanchez, Andrew Glen, Brian Bentz, Jeremy Wright, Sandia National Laboratories

     Abstract Number: 557
     Working Group: Aerosols, Clouds and Climate

Abstract
It is well understood that anthropogenic aerosols play an important role in our global climate, however, the effect of aerosols on cloud microphysical and optical properties is not fully understood. Further, atmospheric models are restricted in their ability to incorporate robust schemes needed to resolve the diffusion and hygroscopic growth of aerosols in a cloudy environment thereby limiting their ability to represent cloud optical properties. To better inform and verify these models, we’ve developed a tabletop fog chamber that can generate polluted clouds under an array of controlled conditions. The chamber is equipped with a suite of instruments that characterize the physical and optical properties of the generated clouds. Specifically, transmissivity is measured with a custom multiband transmissometer, providing transmission data in the visible, SWIR, and LWIR bands. Reflectivity is measured using a quartz-tungsten halogen lamp as the source, arranged coaxially behind a spectrometer, providing reflection data across a wide spectrum of wavelengths. We evaluated the optical properties of clouds generated with different temperatures and relative humidities relevant to the marine boundary layer using varying CCN compositions, concentrations, and sizes. We will discuss insights on the optical impacts of aerosol concentration can be applied to better represent cloud aerosol diffusion in atmospheric models.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.