AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
The Development of a Unique Multi-Wavelength Polar Nephelometer for the Retrieval of Ambient Aerosol Refractive Indices via Reverse Mie Theory
AUSTEN SCRUGGS, Geoffrey Smith, University of Georgia
Abstract Number: 622 Working Group: Instrumentation and Methods
Abstract Ambient aerosols are known to perturb the Earth’s radiative balance via scattering and absorption processes. These perturbations lead to global warming and cooling events that have been shown to significantly contribute to climate change. Irradiance equilibrium perturbations due to direct aerosol-radiation interplay are often quantified via radiative transfer models which employ Mie theory; and thus, rely upon effective refractive indices for aerosol particles which are estimated from particle compositions and their respective abundances, densities, and quintessential refractive indices. However, the refractive indices for some aerosol particles, such as organic carbon particles, are not well understood. Measurements utilizing unique instrumentation focused upon the accurate determination of climate-relevant wavelength dependent aerosol scattering parameters such as the aerosol phase function and scattering asymmetry, are necessary in order to provide accurate refractive indices with minimal uncertainty through reverse Mie theory. Thus, we are developing a unique Multi-Wavelength Polar Nephelometer spanning an angular scattering range of 3° to 177° with high angular resolution. The instrument will be used in conjunction with multi-wavelength photoacoustic and broad band cavity enhanced spectrometers for refractive index retrievals. The instrument development and preliminary retrievals from span gases, 903 nm polystyrene latex particles, and local ambient aerosol are the subject of the current work.